Long-term changes in energy expenditure and body composition after massive weight loss induced by gastric bypass surgery

Das, Sai Krupa; Roberts, Susan B.; McCrory, Megan A.; Hsu, LK George; Shikora, Scott A.; Kehayias, Joseph J.; Dallal, Gerard E.; Saltzman, Edward

doi:10.1093/ajcn/78.1.22

Cited by 187 publications

(140 citation statements)

References 39 publications

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“…Typically, when patients undergo bariatric surgery, rapid weight loss occurs losing both fat mass and fat-free mass which negatively impacts basal metabolic rate 30 . Fat-free mass loss typically accounts for between 33% and 50% of total body mass loss 31 .…”

Section: Discussionmentioning

confidence: 99%

The effects of supervised exercise training 12–24 months after bariatric surgery on physical function and body composition: a randomised controlled trial

et al. 2017

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Section: Discussionmentioning

confidence: 99%

The effects of supervised exercise training 12–24 months after bariatric surgery on physical function and body composition: a randomised controlled trial

et al. 2017

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“…51,50 Given the potential for adverse consequences of this intervention, 61 it is very poorly studied. Although only a small proportion of published results of BPD and LAGB include FFM loss as an outcome, the data concerning these interventions are much more robust than for RYGB.…”

Section: Discussionmentioning

confidence: 99%

Changes in fat-free mass during significant weight loss: a systematic review

2006

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Objective: To identify the proportion of weight lost as fat-free mass (FFM) by various weight loss interventions. Methods: Medline and Embase were systematically searched for reliable measurements of FFM before and after weight loss of 410 kg and eligible data were pooled. In a fixed effect model of % FFM loss/weight loss (%FFML), linear regression analysis was used to determine the influence of degree of caloric restriction, exercise, magnitude of weight loss, initial body mass index (BMI) and type of surgery. Results: Data were included from 26 cohorts treated with dietary and behavioral interventions and 29 cohorts of bariatric surgery patients. The degree of caloric restriction was positively associated with %FFML (r 2 ¼ 0.31, P ¼ 0.006) and in three randomized controlled trials exercise was shown to decrease %FFML. Compared with laparoscopic adjustable gastric banding (LAGB), biliopancreatic diversion (BPD) and roux en Y gastric bypass (RYGB) caused greater log e (natural log) %FFML (r 2 ¼ 0.453, Po0.001). Differences in log e %FFML between surgical procedures were independent of initial BMI and magnitude of weight loss. Conclusions: The degree of caloric restriction, exercise and rate of weight loss influence the proportion of weight lost as FFM after non-surgical interventions. For surgical interventions, BPD and RYGB result in greater %FFML than LAGB.

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“…The group averages for each of seven bariatric surgery studies Required energy deficit per unit weight loss KD Hall whose obese subjects lost an average of 40.5 kg (m) are plotted. 11,[18][19][20][21][22][23] Figure 1a also plots the group averages for four non-surgical weight loss studies whose obese subjects lost an average of 12.5 kg (D). [24][25][26][27] Since these data cluster around the curves predicted by the modified Forbes equation and the horizontal line in Figure 1, both the modified Forbes equation and the simple 32.2 MJ kg À1 rule of thumb approximate the data reasonably well for obese subjects.…”

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What is the required energy deficit per unit weight loss?

2007

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One of the most pervasive weight loss rules is that a cumulative energy deficit of 3500 kcal is required per pound of body weight loss, or equivalently 32.2 MJ kg À1 . Under what conditions is it appropriate to use this rule of thumb and what are the factors that determine the cumulative energy deficit required per unit weight loss? Here, I examine this question using a modification of the classic Forbes equation that predicts the composition of weight loss as a function of the initial body fat and magnitude of weight loss. The resulting model predicts that a larger cumulative energy deficit is required per unit weight loss for people with greater initial body fatFa prediction supported by published weight loss data from obese and lean subjects. This may also explain why men can lose more weight than women for a given energy deficit since women typically have more body fat than men of similar body weight. Furthermore, additional weight loss is predicted to be associated with a lower average cumulative energy deficit since a greater proportion of the weight loss is predicted to result from loss of lean body mass, which has a relatively low energy density in comparison with body fat. The rule of thumb approximately matches the predicted energy density of lost weight in obese subjects with an initial body fat above 30 kg but overestimates the cumulative energy deficit required per unit weight loss for people with lower initial body fat. International Journal of Obesity (2008) When energy intake does not meet energy requirements, the deficit is accounted for by metabolism of stored energy in the form of body fat, protein and glycogen. Since energy is conserved, the metabolizable energy content of the lost tissue is equivalent to the energy deficit required to produce that weight loss. The metabolizable energy density of the lost tissue is therefore determined by its chemical composition. Loss of body water results in a significant mass change, but contributes nothing to the metabolizable energy content. In contrast, the metabolizable energy densities of body glycogen, protein and fat are 17.6, 19.7 and 39.5 MJ kg À1 , respectively. 5 Recently, I developed a modification of the classic Forbes equation 3,4 predicting the proportion of weight loss accounted for by loss of lean body mass as a nonlinear function of both the initial body fat as well as the magnitude of weight loss. 6 On the basis of this equation, the energy density of weight loss can be predicted once the metabolizable energy densities for the lean body mass loss, DL, and body fat mass loss, DF, have been determined.The energy density of the body fat mass change, r F ¼ 39.5 MJ kg À1 is the same as the energy density of fat. It is important to note that the change of body fat, DF, is not equivalent to the loss of adipose tissue, which includes a variable contribution of fluid and protein in addition to triglyceride. 7,8 Rather, DF is the amount of endogenous fat metabolized by the body to meet the energy deficit. Similarly, the energy density of the lea...

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Long-term changes in energy expenditure and body composition after massive weight loss induced by gastric bypass surgery

Abstract: TEE and REE decreased by 25% on average after massive weight loss induced by gastric bypass surgery. REE changes were predicted by loss of body tissue; thus, there was no significant long-term change in energy efficiency that would independently promote weight regain.

Cited by 187 publications

References 39 publications

The effects of supervised exercise training 12–24 months after bariatric surgery on physical function and body composition: a randomised controlled trial

The effects of supervised exercise training 12–24 months after bariatric surgery on physical function and body composition: a randomised controlled trial

Changes in fat-free mass during significant weight loss: a systematic review

What is the required energy deficit per unit weight loss?

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