Factors influencing energy intake and body weight loss after gastric bypass

Abstract

Objective: The gastric bypass-induced quantitative and qualitative modifications of energy intake (En In, kcal=day) and their impact on body weight (bw) loss were evaluated. The factors influencing energy intake and body weight loss were also investigated. Design: Longitudinal study. Setting: University Hospital of Geneva. Subjects: Fifty obese women undergoing a Roux-en-Y gastric bypass. Results: The reduction of EnIn was significantly related to bw loss expressed either in kg or as percentage correction of excess bw (P < 0.01 for both), whereas the post-operative modifications of diet composition did not play a role. Age and initial bw significantly influenced bw loss (P < 0.0001 and P < 0.001, respectively), as shown by multiple regression analysis. Patients were divided into four sub-groups according to their age (under or over 35 y) and initial bw (under or over 120 kg). ANOVA showed that under 35-y-old subjects reduced their EnIn significantly more than their older counterparts having similar bw (P < 0.02 and P < 0.05); consequently, bw loss, expressed in kg, was significantly (P < 0.0001 and P < 0.0005) larger in younger patients. Subjects with an initial bw over 120 kg lost significantly (P < 0.001 and P < 0.02) more weight as compared to patients with a smaller degree of obesity (under 120 kg) and similar age. Conclusions: Gastric bypass-induced body weight loss is mainly due to the reduction of EnIn, whereas the qualitative modifications of the diet do not play a role. Younger subjects have a greater capacity to reduce EnIn and, therefore, lose more weight. Pre-operative high degree of obesity leads to a larger weight reduction, probably because of a greater energy deficit.

Resting energy expenditure and fuel metabolism following laparoscopic adjustable gastric banding in severely obese women: relationships with excess weight lost

“…As already shown, 10,25,26 baseline BMI is independently negatively associated with EWL. But to date, all authors have failed to identify baseline metabolic factors associated with the success of bariatric surgery.…”

Relationship between sympathetic reactivity and body weight loss in morbidly obese subjects

“…In addition, it is clear that the final body weight and/or a possible weight relapse are greatly influenced by the energy intake at the stabilization period. The reduction of energy intake is the main effect of this surgical intervention: 30 in a previous study, 31 we demonstrated that postoperative food intake shows a great individual variability and is influenced by age; in the present study, we suggest that sympathetic excitability could also play a role in the control of energy intake during the stabilization period.…”

“…Together with our previous results, the present study underlines that besides a highly standardized surgical intervention, the weight loss of surgically treated obesity is influenced by several characteristics such as age and initial body weight, 31 their capacity to spare energy 27 and to activate the sympathetic nervous system. These findings could be useful to better understand the large individual variability of body weight loss obtained by bariatric surgery and, more generally, by any weight reduction program.…”

The effect of insulin on cardiac autonomic balance predicts weight reduction after gastric bypass

“…For instance, it has been demonstrated that some psychological traits, such as anxiety and excessive health concerns, are linked to a less satisfactory result after gastric bypass [7], whereas patients showing eating disorders are likely to regain weight at long-term follow-up [8,9]. Among the anthropometric characteristics, initial BMI [10,11] plays an important role in surgically induced body weight loss. Diabetes [12] has also been suggested as a predictor of a lesser weight reduction following bariatric surgery.…”