Metabolic adaptations

Metabolic adaptation increases time to achieve weight-loss goals for premenopausal women

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After a 16% weight loss, premenopausal women with overweight experienced metabolic adaptation associated with a longer time than predicted to achieve weight-loss goals, according to study results published in Obesity.

“Regardless of the extent of metabolic adaptation, its clinical relevance remains to be fully determined,” Catia Martins, MSc, PhD, professor in the department of clinical and molecular medicine and faculty of medicine and health sciences in the obesity research group at the Norwegian University of Science and Technology and the Centre for Obesity and Innovation Clinic of Surgery at St. Olav University Hospital in Trondheim, Norway, and the department of nutrition sciences at the University of Alabama at Birmingham, and colleagues wrote. “It was initially suggested that metabolic adaptation could be a potential explanatory mechanism for long-term weight regain (relapse) as well as resistance to weight loss.”

Scale and tape measure
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Researchers evaluated 65 premenopausal women with overweight (mean age, 36.4 years) with an average BMI of 28.6 kg/m2 who followed an 800 kcal per day diet until their BMI reached 25 kg/m2 or less. Body weight and composition were measured before and after weight loss, and dietary adherence was calculated through total energy expenditure determined by doubly labeled water and composition changes.

Metabolic adaptation was defined as a significantly lower measured vs. predicted resting metabolic rate.

Participants experienced a mean 16.1% (12.5 kg) reduction in body weight over 155.1 days. Dietary adherence, on average, was 63.6%.

After weight loss, measured resting metabolic rate (mean, 1,305 kcal per day) was lower than that predicted (1,351 kcal per day; P = .002).

This metabolic adaptation was a predictor of the length of time needed to reach weight-loss goal (P = .041) and remained after adjusting for confounders (P < .001).

There were no significant associations between metabolic adaptation and target weight loss, energy deficit or dietary adherence. There was also no significant association between metabolic adaptation and the rate of weight loss or the difference between observed and predicted rate of weight loss.

“It needs to be emphasized that this metabolic adaptation was seen after 4 weeks of weight stabilization following the active weight-loss phase and, as such, is probably much lower that what would be expected during the active weight-loss phase. … It is reasonable to expect that metabolic adaptation during active weight loss in the present study may have been closer to 110 kcal per day (46 × 2.42) than 46 kcal per day,” the researchers wrote.

“Further research should confirm these findings in a population of men and women with obesity,” the researchers wrote.

PERSPECTIVE

Fatima Cody Stanford, MD, MPH, MPA, MBA, FAAP, FACP, FAHA, FAMWA, FTOS)

Fatima Cody Stanford, MD, MPH, MPA, MBA, FAAP, FACP, FAHA, FAMWA, FTOS

The concept of metabolic adaptation has become of interest as we recognize the heterogeneity of response to various modalities of interventions to achieve weight loss. In this study by Martins and colleagues published in Obesity, the research team sought to determine whether metabolic adaption played a role in the length of time necessary to achieve weight loss in a diverse cohort of premenopausal women with overweight. The authors concluded that metabolic adaptation ensues after 16% total body weight loss, and it increases the length of time to achieve weight-loss goals.

This study reaffirms that fact that with weight loss, it becomes more challenging to achieve weight-loss goals. This helps inform patients about the difficulty to achieve and maintain weight loss, and it demonstrates that these issues intensify as more weight loss occurs. When patients indicate that weight loss becomes more challenging over time, they should be informed that this metabolic adaptation is leading to their difficulty. This will help to validate their struggles while informing them that these issues align with their biology. Additional tools such as pharmacotherapy (anti-obesity medications), devices and/or metabolic and bariatric surgery might be necessary to assist patients to achieve their weight-loss goals and overcome metabolic adaptation.

Fatima Cody Stanford, MD, MPH, MPA, MBA, FAAP, FACP, FAHA, FAMWA, FTOS

Endocrine Today Editorial Board Member

Obesity Medicine Physician Scientist

Massachusetts General Hospital

Associate Professor of Medicine and Pediatrics

Harvard Medical School

Metabolic adaptations in energy expenditure follow bariatric surgery

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Weight loss after Roux-en-Y gastric bypass, sleeve gastrectomy and laparoscopic adjustable gastric band in patients with obesity may lead to metabolic adaptations in energy expenditure, recently published data show.

Eric Ravussin, PhD, Boyd professor and associate executive director of clinical sciences at Pennington Biomedical Research Center in Baton Rouge, Louisiana, and colleagues evaluated 30 adults (27 women; mean age, 46 years; mean BMI, 47.2 kg/m2) who self-selected bariatric surgery (Roux-en-Y gastric bypass [RYGB], n = 5; sleeve gastrectomy, n = 9; laparoscopic adjustable gastric band [LAGB], n = 7) or a low-calorie diet (n = 9). The low-calorie diet consisted of 800 kcal/day for 8 weeks followed by weight maintenance.

Eric Ravussin

Eric Ravussin

Researchers sought to compare the changes in energy expenditure and circulating cardiometabolic markers 8 weeks and 1 year after bariatric surgery or the low-calorie diet intervention.

Degrees of weight loss were similar between the RYGB and sleeve gastrectomy groups (33%-36%) and were 16% in the LAGB and 4% in the low-calorie diet group after 1 year.

From baseline to week 8 and 1 year, 24-hour energy expenditure and sleeping energy expenditure were reduced in all study groups (P < .05 for all), but 24-hour energy expenditure between baseline and 8 weeks was not significantly reduced in the low-calorie group. From baseline to 8 weeks, after adjustment for free fat mass and fat mass, 24-hour energy expenditure was significantly reduced in all groups (RYGB, –145 kcal/day; sleeve gastrectomy, –254 kcal/day; LAGB, –178 kcal/day; low-calorie diet, –82 kcal/day), but at 1 year the changes persisted only in the RYGB (–124 kcal/day) and sleeve gastrectomy groups (–155 kcal/day). Trends were similar for sleeping energy expenditure in all surgery groups from baseline to 8 weeks (RYGB, –87 kcal/day; sleeve gastrectomy, –275 kcal/day; LAGB, –181 kcal/day), and the changes were maintained at 1 year (RYGB, –134 kcal/day; sleeve gastrectomy, –255 kcal/day; LAGB, –220 kcal/day). Compared with the low-calorie diet group, sleep energy expenditure reductions were higher in all surgery groups at 1 year (P < .05 for all).

One year after RYGB or sleeve gastrectomy, plasma HDL and total and high molecular weight adiponectin were increased, whereas triglycerides and high-sensitivity C-reactive protein levels were reduced.

“We found that metabolic adaptation of [approximately] 150 kcal [per day] occurs up to 1 year after RYGB, [sleeve gastrectomy] and LABG surgery,” the researchers wrote. “Our findings in obese individuals after bariatric surgery extend those already available after diet-induced weight loss, suggesting that a deficit in energy adaptation may be a homeostatic mechanism encouraging weight regain. Future studies are required to examine whether these effects remain beyond 1 year and contribute to the metabolic benefits of bariatric surgery.” – by Amber Cox