To Keep Myself on Track: The Impact of Dietary and Weight Monitoring Behaviors on Weight Loss After Bariatric Surgery

Abstract

Background:

Dietary and weight monitoring are effective strategies for weight loss among individuals using dietary and lifestyle weight management techniques. This study aimed to (1) examine self-monitoring behaviors in bariatric surgery patients, (2) identify the effect of self-monitoring behaviors on postsurgery weight loss, and (3) describe patients' explanations for performing self-monitoring behaviors.

Methods:

Thirty participants (24 women, 6 men) scheduled for either gastric bypass (n = 11) or sleeve gastrectomy (n = 19) were recruited to participate in a year-long, observational study of dietary and weight management behaviors. Twenty-nine completed self-monitoring questionnaires presurgery; 22 participants were available at the 6- and 23 were available at the 12-month follow-up.

Results:

Baseline dietary and weight monitoring behaviors positively correlated with performance of those behaviors at 12 months (p < 0.05). Dietary monitoring behaviors at 12 months were positively correlated to total weight lost and percent excess weight loss at 12 months (p < 0.05). Weight monitoring was not related to weight outcomes. Participants' explanations for monitoring behaviors included accountability, keeping track of food or nutrient intake, and monitoring weight loss or preventing weight gain.

Conclusion:

Dietary monitoring may be a useful weight loss strategy following bariatric surgery. Further research is needed to examine the long-term benefits of dietary and weight monitoring behaviors.

Introduction

Although bariatric surgery is considered the most successful treatment for obesity, not all patients experience successful weight loss, commonly defined as losing >50% excess body weight,¹ and significant weight regain has been reported long-term in some patients.^2,3 Both suboptimal weight loss and weight regain are concerning outcomes of weight loss surgery, and therefore, behaviors that promote and maintain weight loss among nonsurgical dieters may be appropriate for the bariatric population. Weight and dietary monitoring are consistently and positively associated with weight loss and weight loss maintenance in nonsurgical dieters;⁴ however, little attention has been given to the role of these behaviors in promoting positive weight loss outcomes among bariatric surgery patients.

Self-monitoring involves keeping a record of a particular behavior (e.g., food diary and physical activity log) or regularly monitoring a desired outcome such as weight. It is an essential component of the self-regulation of behavior. Self-regulation theory explains behaviors as intentionally enacted to reach a desired goal or outcome.⁵ Self-monitoring provides a way for individuals to increase their awareness of body processes or changes and serves as a tool for individuals to track behaviors.⁶ Self-monitoring, therefore, is a process by which individuals can track performance of goal-directed behaviors to understand if those behaviors are facilitating goal achievement.⁵

The two main types of self-monitoring examined in the weight loss literature are self-weighing, usually defined as checking weight with a scale, and tracking dietary intake, typically with food records. Self-weighing is associated with greater initial weight loss⁷ and better long-term weight loss maintenance.^8–10 Inconsistency or reductions in self-weighing frequency have been observed to lead to weight gain.^11,12 Similarly, dietary monitoring has also been associated with improved weight loss outcomes and long-term weight management.¹³ Both smartphone apps and traditional (i.e., paper) food records have positive effects on weight loss.¹⁴ Finally, research suggests that the frequency of dietary monitoring is more important than detail or comprehensiveness.^13,15,16

Four studies, one prospective and three retrospective, have examined the effect of self-monitoring among bariatric patients. Self-weighing after surgery has been associated with greater weight loss at 3 years postoperatively¹⁷ and has been reported by patients with successful weight loss maintenance.¹⁸ Dietary monitoring has also been associated with both short- and long-term weight loss.^17,19 Finally, among patients an average of 28 months postsurgery, those who reported self-monitoring behaviors (both dietary and weight) were more likely to have maintained weight loss.²⁰ These few studies suggest that self-monitoring may have positive impact on weight loss outcomes; however, a majority of these have been retrospective, cross-sectional studies. Further research is needed to provide support for these initial findings and improve understanding of the specific behaviors and rationales behind monitoring behaviors.

This study was undertaken to identify the frequency of self-monitoring behaviors both pre- and postsurgery and to examine the effect these behaviors have on weight loss at 1 year. It also aimed to capture patients' explanations for the use of monitoring behaviors, as little is known about what and/or why individuals monitor.

Methods

Recruitment

Participants were recruited from an American Society of Bariatric and Metabolic Surgery-accredited surgery center at the time of their final presurgery education class to participate in a mixed methods study examining dietary, weight, and lifestyle changes following bariatric surgery. Both gastric bypass and sleeve gastrectomy patients were eligible to participate if they were older than 18 years and had a surgery date scheduled. Participation involved meeting with the lead researcher three times (presurgery and at 6 and 12 months postsurgery) for an in-depth, qualitative interview followed by completion of surveys and questionnaires related to diet, physical activity, and medical history.

Thirty participants (19 sleeve gastrectomy and 11 gastric bypass) volunteered to participate. The ratio of sleeve gastrectomy to gastric bypass participants is similar to the ratio of surgery patients seen at that time. Weight and height were obtained through medical records. Participants received a food scale at the first interview and were monetarily compensated for their time. All study procedures were approved by the institutional review boards of both the sponsoring university and hospital. Written informed consent was obtained at the beginning of the first presurgery meeting.

Questionnaire development

The self-monitoring questionnaire, which surveys both dietary and weight self-monitoring behaviors, was previously pilot tested.¹⁹ Dietary monitoring questions measured three different diet monitoring behaviors: keeping food records, mentally tracking dietary intake, and weighing or measuring food. Weight monitoring questions assessed frequency of tracking weight using a scale.

The dietary monitoring behavior recording food and drink was assessed with a question asking participants, “How often do you currently write down or record what you eat and drink in a day?” with nine potential answers from several times a day to never. A second question about recording food intake asked “Thinking back over the past week, how many days did you write down or record what you ate and drank?” with selections ranging from 0 to 7 days. Similar questions were asked about mentally tracking intake and weighing or measuring foods. Open-ended questions asked participants why they performed (or did not perform) the monitoring behaviors of recording dietary intake and mentally tracking intake. Finally, participants were asked to identify how often they used specific portion control methods such as using a food scale, measuring cups, or specific serving containers.

To assess weight monitoring, participants were asked “How often do you check your weight with a scale?” with nine potential answer choices ranging from several times a day to never and “Thinking back over the past week, how many days did you check your weight with a scale?” with answers ranging from 0 to 7 days. They were also asked to identify how often they used alternative methods to check their weight, including clothing size or fit, body measurements, and how they look or feel. A single open-ended question asked participants why they did (or did not) check their weight with a scale.

Baseline and 6-month questionnaires were identical. Additional questions were added to the 12-month questionnaire, including an open-ended question about rationales for weighing/measuring food. Additional questions focused on the use of journaling for emotions and the use of technology, including what types of technology participants used and what they tracked (e.g., calories, protein, steps, and weight) because of the increased adoption of smart phone apps by participants at the time.

Statistical analysis

Four different weight loss outcomes were calculated to evaluate weight change between time points (baseline presurgery, 6 months postsurgery, and 12 months postsurgery) in accordance with standardized reporting of weight loss outcomes following bariatric surgery:²¹ \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} \begin{align*}{ \rm Absolute}{ \rm{ }} \ { \rm weight} \ { \rm loss} \; \; = \;{ \rm weight} \ { \rm{ }} \left( {{ \rm kg} , { \rm{ }} \ { \rm time} \ { \rm{ }}1} \right) \; \\ - \;{ \rm weight} \ { \rm{ }} \left( {{ \rm kg} , \ { \rm{ }}{ \rm time} \ { \rm{ }}2} \right) .\end{align*} \end{document} \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} \begin{align*}{ \rm Percent}{ \rm{ }} \ { \rm weight}{ \rm{ }} \ { \rm loss} \; = \;{ \rm absolute}{ \rm{ }} \ { \rm weight}{ \rm{ }} \ { \rm loss} / \\{ \rm weight}\;{ \rm{ }} \left( {{ \rm kg} , { \rm{ }}{ \rm time} \ { \rm{ }}1} \right) .\end{align*} \end{document} \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} \begin{align*}{ \rm BMI}{ \rm{ }} \ { \rm unit}{ \rm{ }} \ { \rm change} \; = \; { \rm BMI} \ { \rm{ }} \left( {{ \rm kg} / {{ \rm m}^2} , { \rm{ }} \ { \rm time} \ { \rm{ }}1} \right) \; \\- \; { \rm BMI}\;{ \rm{ }} \left( {{ \rm kg} / \ {{ \rm m}^2} , { \rm{ }}{ \rm time} \ { \rm{ }}2} \right) .\end{align*} \end{document} \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} \begin{align*}{ \rm Excess}{ \rm{ }} \ { \rm percent}{ \rm{ }} \ { \rm weight}{ \rm{ }} \ { \rm loss} \; = \; { \rm absolute}{ \rm{ }} \ { \rm weight}{ \rm{ }} \ { \rm loss} / \ \\{ \rm { \rm weight}}{ \rm{ }} \ \left( {{ \rm kg} , \ { \rm{ }}{ \rm time} \ { \rm{ }}1} \right) \; \\- \;{ \rm ideal}{ \rm{ }} \ { \rm body} \ { \rm{ }}{ \rm weight} \ { \rm{ }} \left( {{ \rm kg}} \right) ,\end{align*} \end{document}

where ideal body weight is a participant's weight in kilograms at a body mass index (BMI) of 25 kg/m².

Weight outcomes were not normally distributed; therefore, data were analyzed using nonparametric statistical tests. Differences in weight outcomes between independent groups, such as surgery type, were evaluated using Wilcoxon rank-sum tests. Spearman's correlation tests were used to assess relationships between self-monitoring variables and between self-monitoring and weight outcomes. Categorical variables were examined using chi-square and Fisher's exact tests. Means are presented with standard deviations. Significance was established at p < 0.05. All quantitative data were analyzed using SAS 9.3 (Cary, NC).

Open-ended data analysis

Open-ended questions asked participants why they chose to engage in a particular monitoring behavior, such as “Please describe the reasons you write down or record what you eat and drink. If you do not write down or record what you eat and drink, please describe the reasons you do not.” Answers to open-ended questions were input verbatim into a spreadsheet and organized by time point. Each answer was coded based on the concept(s) represented. Responses were then organized into themes and themes were compared between the time points.

Results

Participant characteristics

Out of 30 participants at baseline, 1 did not complete all questionnaires, including the self-monitoring questionnaire. Twenty-two of the remaining 29 completed self-monitoring questionnaires at the 6-month follow-up and 23 completed them at the 12-month follow-up. Two participants missed the 6-month follow-up due to time conflicts. Reasons other participants were lost to follow-up were unable to be determined, as participants did not return researcher's calls, including two who did not show up for scheduled meetings.

Participant characteristics are presented in Table 1. A majority of the participants were female (n = 24) and white (n = 23). The average age was 45.3 years (±11.3) with a range of 19–68 years. Over half of the participants were married and 31% had children living at home. Mean weight at baseline was 129.9 kg (±27) and mean BMI was 47.7 kg/m² (±7.8). The average time participants had been patients at the bariatric surgery center was 6.4 months with a range of 64–375 days. Differences were largely dependent on preoperative insurance requirements.

Table 1.

Baseline Characteristics of 29 Bariatric Surgery Patients

	Number	Percent
Sex
Females	24	82.8
Males	5	17.2
Race
White	23	79.3
Black	6	20.7
Surgery type
Gastric bypass	11	37.9
Sleeve gastrectomy	18	62.1
Marital status
Never married	8	27.6
Married	16	55.2
Other	5	17.2
Employment
Full time	15	51.7
Other	14	48.3
Education
High school graduate	2	6.9
Some college	12	41.4
College or graduate degree	15	51.7
Income
<$60,000 (%)	14	48.3
$60,000 and above (%)	14	48.3
Not reported (%)	1	3.4

Participant weight changes

Table 2 summarizes weight outcomes at baseline, 6 months, and 12 months postsurgery. Total weight and BMI were significantly lower at 6 and 12 months, with significantly greater changes in weight, BMI, and percent weight loss between baseline and 6 months compared with 6 and 12 months (p < 0.001 for all values, data not shown). There were no significant differences in weight variables or outcomes between the two surgery types at any of the time points. Changes in weight and BMI among those who did and did not return the self-monitoring questionnaires at 6 and 12 months were not significant.

Table 2.

Presurgery, 6 Months, and 12 Months Weight Outcomes Among Bariatric Surgery Patients

	Presurgery	6 months	12 months
n	29	22	23
Weight (kg)	129.9 (24.9)	98.5 (14.2)^*	92.0 (15.2)^,*
BMI (kg/m²)	47.7 (7.8)	36.2 (5.3)^*	33.6 (5.5)^,*
Absolute weight loss (kg)^a	–	29.4 (7.2)	35.7 (10.0)^**
Percent weight loss, % (SD)^a	–	22.8 (4.0)	27.9 (6.9)^**
BMI unit change (kg/m²)^a	–	10.7 (2.4)	13.0 (3.7)^**
Percent excess weight loss, % (SD)^a	–	51.0 (12.1)	62.6 (17.3)^**

All values expressed as mean (SD).

\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $${ \rm Absolute} \ { \rm{ }}{ \rm weight} { \rm{ }} \ { \rm loss} \; = \;{ \rm weight} \ \left( {{ \rm baseline}} \right) \; - \;{ \rm weight} \ { \rm{ }} \left( {\rm timepoint} \right)$$ \end{document}

\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $${ \rm Percent} \ { \rm weight} \; { \rm loss} \; = \; { \rm absolute} \; { \rm weight} \; { \rm loss} / { \rm weight} \; \left( {{ \rm baseline}} \right)$$ \end{document}

\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $${ \rm BMI} \; { \rm unit} \; { \rm change} \; = \; { \rm BMI} \; \left( {{ \rm baseline}} \right) \; - \; { \rm BMI} \; \left( {{ \rm timepoint}} \right)$$ \end{document}

\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $${ \rm Percent} \; { \rm excess \; weight \; loss} = { \rm absolute \;weight \; loss} / \\ \rm {weight} \; \left( {{ \rm baseline}} \right) -{ \rm ideal \; weight} \; \\ \left( {{ \rm weight \; at \; a \; BMI \; of} \; 25} \right)$$ \end{document}

Significantly different from baseline, p < 0.001.

Significantly different from 6 months, p < 0.001.

Change since baseline.

BMI, body mass index; SD, standard deviation.

Self-monitoring behaviors

Frequency of self-monitoring behaviors

Mentally tracking food intake was the most frequently reported behavior at all time points. Self-weighing was the least likely to be reported on a daily basis. More participants weighed themselves weekly, particularly post-surgery. The proportion of participants who weighed or measured food changed over the course of the study; over half of the participants reported never weighing/measuring food at baseline and less than a quarter answered never at 6 and 12 months. Recording food and drink decreased in frequency by 12 months, with over a third of participants reporting never doing so at that time. Figure 1 shows the frequencies of monitoring behaviors at each study time points.

FIG. 1.

Changes in the frequency of self-monitoring behaviors from presurgery to 12 months postsurgery. Never (), yearly (), monthly (), weekly (), and daily ().

Relationships between self-monitoring behaviors

The performance of individual monitoring behaviors was fairly consistent over time. Self-weighing at baseline and at 6 months both positively correlated with self-weighing at 12 months (r = 0.56 p = 0.01 and r = 0.77 p < 0.01, respectively), but the relationship between self-weighing at baseline and 6 months was not significant (r = 0.38 p = 0.09). Similarly, recording food and weighing/measuring food were positively correlated between baseline and 6 months (r = 0.47 p = 0.03 and r = 0.45 p = 0.04, respectively) and between 6 and 12 months (r = 0.65 p < 0.01 and r = 0.53 p = 0.02, respectively).

Different monitoring behaviors correlated with one another at different time points. At baseline and 6 months, dietary self-monitoring behaviors did not correlate with each other but at 12 months, weighing/measuring food and recording food were positively correlated with each other (r = 0.55 p = 0.01). Some correlations were behavior and time discordant. Recording food at baseline positively correlated with mentally tracking intake at 6 months (r = 0.54 p = 0.02) and the reverse was also true—mentally tracking at baseline correlated with recording food at 6 months (r = 0.47 p = 0.03). Self-weighing at baseline positively correlated with recording intake at 6 months (r = 0.47 p = 0.03) and 12 months (r = 0.54 p = 0.01). Weighing/measuring food at baseline was negatively correlated with self-weighing at 6 months (r = −0.54 p = 0.01).

Alternative methods for self-monitoring

Patients' use of alternative dietary and weight monitoring methods is displayed in Tables 3 and 4. There was an increase in the number of participants who “always” or “often” used a food scale, measuring cups and spoons, small plates, and bowl of a known amount between baseline and 6 and 12 months. There was a decrease in the number of participants who “always” or “often” used visual estimates at 6 months with an increase at 12 months. More participants used clothing size and “how I feel” to assess their weight postsurgery than presurgery. Body measurements were infrequently used at all time points and were used either monthly or yearly.

Table 3.

Methods for Portion Control and Weight Monitoring Reported by Bariatric Surgery Patients from Presurgery to 12 Months Postsurgery

	n	Always	Often	Sometimes	Never
Presurgery
Food scale	25	0.0%	24.0%	16.0%	60.0%
Measuring cups/spoons	27	25.9%	22.2%	14.8%	37.0%
Bowl of known amount	27	22.2%	18.5%	18.5%	40.7%
Small plate	26	38.5%	26.9%	15.4%	19.2%
Visual estimate/guess	27	33.3%	37.0%	25.9%	3.7%
6 months postsurgery
Food scale	22	22.7%	45.5%	4.5%	27.3%
Measuring cups/spoons	21	23.8%	47.6%	14.3%	14.3%
Bowl of known amount	21	33.3%	38.1%	23.8%	4.8%
Small plate	21	42.9%	33.3%	23.8%	0.0%
Visual estimate/guess	21	14.3%	23.8%	57.1%	4.8%
12 months postsurgery
Food scale	22	13.6%	36.4%	13.6%	36.4%
Measuring cups/spoons	22	9.1%	50.0%	27.3%	13.6%
Bowl of known amount	23	30.4%	43.5%	8.7%	17.4%
Small plate	23	43.5%	39.1%	4.3%	13.0%
Visual estimate/guess	23	34.8%	30.4%	30.4%	4.3%

Table 4.

Alternative Methods for Checking Weight Reported by Bariatric Surgery Patients from Presurgery to 12 Months Postsurgery

	n	Daily	Weekly	Monthly	Yearly	Never
Presurgery
Clothing size	28	25%	21%	25%	7%	21%
Body measurements	28	0%	4%	14%	25%	57%
Look in mirror	28	54%	11%	7%	7%	21%
Feel	28	43%	32%	4%	0%	21%
6 months
Clothing size	22	32%	27%	27%	5%	9%
Body measurements	22	5%	5%	32%	27%	32%
Look in mirror	22	68%	14%	14%	0%	5%
Feel	22	64%	18%	5%	0%	14%
12 months
Clothing size	23	48%	13%	26%	0%	13%
Body measurements	23	0%	4%	13%	39%	43%
Look in mirror	23	52%	30%	4%	0%	13%
Feel	23	61%	26%	4%	0%	9%

At 12 months, 17 participants were actively using technology to track monitor their behaviors. A majority (11) used apps on their smart phones or tablets; one used a wearable activity tracker.

Self-monitoring behaviors and weight outcomes

Self-monitoring behaviors correlated with changes in weight loss outcomes between presurgery and 6 months and between 6 and 12 months. Frequency of recording intake was related to percent weight loss between 6 and 12 months (r = 0.435 p = 0.0378) and to percent excess weight loss between 6 and 12 months (r = 0.4195 p = 0.0463). Weekly weighing of food correlated to percent excess weight lost between baseline and 6 months (r = 0.4772 p = 0.0287). Change in BMI was not related to any monitoring behaviors at either time point. Neither mentally tracking intake nor self-weighing was significantly correlated with weight outcomes at any time point.

Explanations for monitoring behaviors

Mentally tracking intake

The themes of accountability, staying on track, and increased awareness were present at all three time points in participants' explanations for mentally tracking intake. Participants tracked calories, protein, water, and carbohydrates, with more participants identifying nutrients at 6 months than other time points. A unique theme emerged at 12 months: mentally tracking to prevent unwanted eating habits or to adjust future food consumption. Reasons for not mentally tracking varied across time points and several did not provide an explanation.

Recording food intake

At all time points, the most common theme for why participants used food records was “keeping track.” Participants often mentioned calories in presurgery questionnaires, while protein and water were most commonly recorded postsurgery. Themes of accountability, awareness, and staying on track were also present at all time points. At 12 months, controlling intake and linking intake to weight were two newly occurring themes. Presurgery, the main reason for not recording intake was lack of motivation. Postsurgery, reasons varied, including not seeing a need because it did not affect weight or because they ate the “same thing every day.”

Checking weight with a scale

At baseline, a majority of participants who regularly checked their weight did so for monitoring purposes. At 6 months, a majority of participants checked their weight to monitor their weight loss progress. At 12 months, participants checked weight to monitor or keep track and to watch for weight gain. Barriers to checking weight with a scale at all time points included fear, using other methods, or relying on clinic visits to check their weight.

Weighing or measuring food

The two emergent themes in the explanations for weighing or measuring food at 12 months postsurgery were portion control (reported by seven participants) and/or preventing overeating (reported by four). Ensuring adequate nutrition in the form of consuming from all food groups or protein was identified by four participants. Of the participants who did not weigh or measure their food, four participants stated they used feelings of fullness or visual estimates. Four participants did not respond to this question.

Table 5 provides details of patients' explanations for engaging in the self-monitoring behaviors of mentally tracking intake, recording food intake, and checking weight with a scale.

Table 5.

Themes for Open-Ended Responses Explaining the Use of Self-Monitoring Methods Pre- and Post-Bariatric Surgery

	Presurgery	6 months postsurgery	12 months postsurgery
Mentally tracking intake
Explanations for mentally tracking intake Presurgery: 27 responses 6 months: 17 responses 12 months: 20 responses	Keeping track (6) - food choices, protein, water, carbohydrate Accountability (6) Awareness of food intake (4) Aid in accuracy of food records (4) Planning ahead for future meals (3) Control intake/avoid overeating (3) Instead of keeping food record (2) Focus on weight loss (2) Habit (1) Preparing for surgery (1)	Ensure meeting goals (7) - protein, water Awareness of intake (4) Accountability (2) Identify foods that cause negative effects (1) Avoid overeating (1) Aids in food records (1) Instead of keeping food records (1)	Monitor intake or stay on track (5) Prevention of unwanted eating habits (3) Planning future meals (2) Instead of food records (2) Remain mindful (2) Relate to weight changes (1) Prevent weight gain (1)
Explanations for not mentally tracking intake Presurgery: 1 response 6 months: 3 responses 12 months: 1 response	No need/desire (1) No response (1)	Keep track with other methods (2) No time (1) No response (3)	Forget (1) No response (2)
Recording food
Explanations for keeping food records Presurgery: 23 responses 6 months: 16 responses 12 months: 12 responses	Keeping track (13) - calories, protein, carbohydrates, food choices, amount of food, habits Accountability (5) Stay on track (3) - schedule, weight loss Awareness (1) Eat less (1) Requirement (1)	Keeping track (14) - protein, water, calories, sugar, food choices, blood sugar Stay on track (2) Awareness (2) Accountability (1)	Keep track (9) - protein, calories, water, food choices Control intake (3) Link intake with weight (2) Accountability (1) Awareness of intake (1)
Explanations for not keeping food records Presurgery: 6 responses 6 months: 5 responses 12 months: 8 responses	No motivation (5) Never considered (1) Dislike (1)	No need (2) - eat same thing daily Dislike (1) Lack of time (1) Do not keep notes with me (1) No response (1)	Anxiety/stress (4) Lack of time (2) Does not affect weight (2) Work conflicts (1) Forget (1) Boredom (1) No response (3)
Checking weight with a scale
Explanations for checking weight Presurgery: 17 responses 6 months: 15 responses 12 months: 16 responses	Monitor weight loss (9) Keep track (4) Positive reinforcement for behaviors (2) Be proactive about weight changes (1) Monitor diet effectiveness (1) Awareness of what does/does not work (1)	Monitor/keep track of progress with weight loss (11) Consistent habit (3) Reinforcement (2) Curiosity (1) Ensure no weight gain (1)	Monitor/keep track of weight or progress (6) Watch for weight gain (6) Assess need for changes (2) See how “body responds to certain events” (1) Habit (1) Accountability (1)
Explanations for not checking weight Presurgery: 9 responses 6 months: 4 responses 12 months: 5 responses	Use other methods (3) - “how I feel,” guess, clothing fit Weigh at clinic only (2) Fear of becoming obsessed (1) “just did not” (1) Fear of number (1) No scale at home (1) No response (3)	Only weigh at clinic (2) Fear of discouragement if weight loss is slow (1) Use clothing fit instead (1) No response (3)	Forget (2) Use clothing fit (1) Fear of number (1) No time (1) No response (3)

Discussion

This study sought to describe the dietary and weight monitoring behaviors of bariatric surgery patients and to examine the relationships of these behaviors with weight loss outcomes 1 year postoperation. Results from a self-monitoring survey indicate that bariatric surgery patients use a variety of different self-monitoring strategies but that use changes with time. More participants used monitoring strategies at 6 months than at 12 months. Postsurgery percent weight loss was significantly correlated to the frequency of recording food intake at both 6 and 12 months, and percent excess weight loss between 6 and 12 months was associated with weekly weighing of food reported at 12 months.

Results of this study support previous work on self-monitoring behaviors and weight outcomes following bariatric surgery. Lynch and Bisogni¹⁹ also found that dietary monitoring, but not weight monitoring, was related to percent excess BMI loss and percent weight loss maintained in gastric bypass patients who were an average of 15 months postsurgery. Mitchell et al.¹⁷ identified the specific monitoring behavior of recording fat intake as correlated to greater weight loss outcomes at 3 years. Thus, dietary monitoring may be related to short- and long-term weight outcomes.

Participants in this study indicated that monitoring helped them “stay on track” and increased “awareness,” themes that were also uncovered in a qualitative study on the experiences of self-monitoring in a traditional weight loss intervention.²² The act of recording food may make participants more mindful of their intake, which could influence their food choices and portion sizes. It could also be a sign of commitment to change. Several studies have identified the concepts of vigilance, commitment to new dietary behaviors, gaining control, and needing to “work” for successful weight loss.^23–25 Recording and weighing food take time and effort. Thus, participants who are more likely to practice these behaviors may be more motivated or have a greater sense of personal responsibility.

Lack of significant relationships between weight monitoring and weight loss may be due to the fact that patients lose up to 60% excess body weight in the first year²⁶ with weight loss often continuing for 18–24 months.¹ As most patients rapidly lose large amounts of weight, 1 year is likely not long enough to identify a positive effect of weight monitoring. This strategy, however, is likely more effective in promoting weight loss maintenance. Data from the National Weight Control Registry, which consistently finds positive relationships between weight loss maintenance and self-weighing, include participants who have maintained weight loss for at least a year.^11,27,28 There is evidence that self-weighing after gastric bypass and laparoscopic banding is related to greater weight loss at 3 years postoperation.¹⁷ More long-term studies need to be conducted to see if this is a useful strategy after bariatric surgery.

Among nonsurgical populations, more frequent weight monitoring (checking weight daily, weekly, or monthly) positively correlates to greater weight loss and weight loss maintenance.⁸ Individuals who monitor their weight also perform more weight control behaviors such as reducing snack and dessert intake, increasing steps, and reducing television viewing time.²⁹ From a self-regulation perspective, checking weight regularly would alert individuals to small gains, which can more easily be managed than larger gains. It is interesting to note that at 12 months, 37% of patients who reported checking their weight did so to remain alert to weight regain. In addition, patients' reactions and responses to checking their weight need to be examined, as a few participants in this study described fear of becoming obsessed with weight or of seeing regain. These barriers would need to be addressed as this could signal lack of self-efficacy in managing weight, unrealistic weight loss expectations, or other cognitive-behavioral issues that might present challenges to long-term success.

Participants in this study were all patients from a single bariatric surgery program who received standardized preoperative dietary counseling, including recommendations to keep food records and weigh themselves at least once a week. The fact that more participants checked their weight weekly than daily suggests that they were adhering to general recommendations by healthcare practitioners to check their weight weekly. Frequency of weighing food and using a food scale increased between baseline and 6 months. The increase in this behavior may be due to the fact participants were given a food scale as an incentive to participate. At 6 months, participants were likely still adjusting to their altered digestive tracts and recording and weighing food may have been a way to control portion sizes or identify problem foods to prevent negative effects of overeating (e.g., vomiting or dumping syndrome),³⁰ as mentioned by a few participants in their open-ended responses.

Over half of participants monitored food intake by recording and/or weighing/measuring food at both 6 and 12 months after surgery. Previous work suggests that postgastric bypass patients use dietary and weight monitoring methods to manage weight long term, enabling them to maintain weight or immediately address weight gain.³¹ While only two participants linked dietary monitoring behaviors to weight, many participants specifically tracked nutrients postsurgery, with protein and water being the most common. This is also consistent with recommendations from clinic staff. Studies suggest that protein intake frequently decreases after surgery and that a majority of patients are not meeting protein needs.^32,33 Dehydration is also a concern, given the limited stomach capacity and is a common cause for postoperative hospital visits.^34,35 Postsurgery, patients frequently underconsume important nutrients (e.g., iron and protein) and are not always compliant with supplement recommendations, increasing risk for deficiencies.^32,33,36 Encouraging patients to track dietary intake and having them focus on important nutrients may be a strategy to improve nutritional outcomes.

Sleeve gastrectomy and gastric bypass both promote weight loss through surgical alteration of the digestive tract that restricts quantity of food consumed and alters hunger and satiety signaling.³⁷ Research on differences in weight outcomes between the two surgeries has yielded conflicting results. Studies indicate greater weight loss with the gastric bypass,^38,39 with the sleeve gastrectomy,⁴⁰ or no differences between the two surgery types.⁴¹ No differences in weight outcomes between the two surgery groups were observed in this study nor were there differences in monitoring behaviors. Lack of differences in monitoring behaviors may be due to participants receiving the same pre- and postoperative counseling; however, given that gastric bypass surgery typically leads to more negative consequences of overeating and more food intolerances, monitoring dietary intake might be a useful strategy for patients as they adapt to new ways of eating.

The findings of this study must be considered in light of the limitations. This was a prospective study, but the sample size was small (n = 30 at baseline) and 23% were lost to follow-up. Although there were no differences in weight outcomes between those who participated for the full year, and those who did not, there is still the possibility that there were differences in behaviors or characteristics that could have affected the outcomes. The short-term follow-up in this study also prevents conclusions regarding successful long-term weight maintenance, which is ultimately the goal of bariatric surgery. Finally, participants in this study were primarily white females, limiting generalizability to men and other racial groups. Although the ratios of men to women and black to white participants were similar to those seen in the clinic, future research needs to include a greater representation of men and minorities.

Conclusion

This prospective study assessed self-monitoring behaviors among a small cohort of bariatric surgery patients and found a significant, positive relationship between dietary monitoring and weight outcomes at both 6 and 12 months postsurgery. Dietary monitoring in particular may be a useful weight loss strategy in the first year following bariatric surgery, and it may also have a role in preventing nutritional deficiencies. Although weight monitoring was not related to weight loss outcomes at 1 year, it may be an important habit for patients to develop, given that long-term weight loss maintenance is frequently related to weight monitoring. Dietary and weight monitoring behaviors could enhance individuals' awareness of the link between their food choices, portion sizes, and weight and nutritional outcomes postsurgery. These strategies should be encouraged among all postoperative bariatric surgery patients.

Footnotes

Acknowledgment

This study was funded, in part, by the Oakland University-Beaumont Multidisciplinary Research Award.

Author Disclosure Statement

No competing financial interests exist.

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