The rate of weight loss does not affect resting energy expenditure and appetite sensations differently in women living with overweight and obesity
Introduction
The ‘ideal’ rate of weight loss as well as its clinical implications in weight management have been discussed repeatedly in the literature [1,2]. The belief that a slower weight loss is associated with a better weight loss maintenance has been investigated and recently questioned [[3], [4], [5], [6]]. In fact, there is evidence that a higher percentage of individuals engaged in the rapid weight loss (81% vs 62% of the slow weight loss) were able to achieve the target goal for the maintenance phase [3]. Along the same lines, individuals enrolled in a rapid weight loss group were found to be five times more likely to achieve 10% weight loss at 18 months compared to the individuals enrolled in a slow weight loss group [5]. Furthermore, results have demonstrated that individuals who engaged in weight loss interventions with different degrees of caloric restriction presented similar weight regain after 9-month [4], 1-year [5] and 144-week [3] follow-up period.
The high rates of weight relapse commonly observed after weight loss are mainly attributable to compensatory mechanisms that relate either to energy intake (EI) or to energy expenditure (EE) [[7], [8], [9]]. The existence of metabolic adaptations following weight loss seems to be well established in the literature; however, not many studies have investigated whether different types of diet and/or degrees of caloric restriction impact the magnitude of those compensatory changes [3,10,11]. Available literature on the rate of weight loss also reveals group differences as far as the final weight loss is concerned [11,12]. Considering the existence of an association between the magnitude of weight loss and the extent of metabolic adaptations [[13], [14], [15], [16]], studies aiming to investigate whether the rate of weight loss influences metabolic adaptations need to control for the differences in total weight loss.
Siervo et al [11] noted significant decreases in TEE and REE following 10% of weight loss in groups under very low-calorie diet (VLCD- rapid weight loss) and low-calorie diet (LCD – slow weight loss); TEE decreases were similar in both groups whereas changes in REE were greater in the slow weight loss arm [11]. Of note, the first study [11] was only performed in men, and participants from different groups presented different weight loss, which is an important confounder of the changes in these variables. In contrast, Coutinho et al. [10] did not report any differences in REE after 10% weight loss in individuals engaged in either rapid or slow weight loss groups after the refeeding period, whereas after the weight loss period, the rapid weight loss presented higher decreases in REE.
Results related to the effects of different weight loss rates on appetite are also incongruent. After reaching a minimum of 12.5% weight loss, only participants in the rapid weight loss presented significant increases in hunger ratings (measured by Visual Analogue Scale- VAS) at 44 and 144-week of follow-up period [3]. On the other hand, another study noted that only slow weight loss promoted significant increases in fasting Prospective Food Consumption (PFC), whereas greater decreases in postprandial fullness and hunger immediately after the intervention period were noted in the rapid weight loss group [10]. No differences were observed after the refeeding period. It is important to note that some of these studies differ in terms of design. Purcell et al. [3] excluded results of participants who did not reach the minimum predicted weight loss (−12.5%), which resulted in a higher proportion of participants from the rapid weight loss group (vs. slow weight loss) being included in the analyses.
Taken together, findings point out to the necessity of further investigations on the effects of different rates of weight loss on EI and EE adaptations. To our knowledge, no study has investigated the effects of different rates of weight loss on palatability and olfactory performance together with measures of REE, fasting and postprandial appetite. Accordingly, the purpose of the present study was to investigate the changes in REE, appetite sensations, olfaction, palatability and EI in pre-menopausal women who lost a similar amount of body weight while engaged in either a slow (−500 kcal/ day, 20 weeks) or a rapid (−1000 kcal/day, 10-week) weight loss program. We hypothesized that both slow and rapid weight loss would lead to similar REE and appetite changes following weight loss in premenopausal women living with obesity.
Section snippets
Subjects
A total of 36 women who were premenopausal and living with overweight and obesity -were enrolled in the program. Thirty women completed the intervention. The inclusion criteria were as follows: 27 ≥ BMI < _40 kg/m2, 18 years and older, waist circumference > 88 cm, weight-stable (±2 kg last 6 months), inactive (<150 min per week), no history of alcohol or drugs abuse, no food allergies, non-smoker, pre-menopausal with a regular menstrual cycle, not pregnant, not taking any medication that can
Results
During the intervention period, 6 participants (or 16.7%) quit the study. Reasons included lack of motivation (3), lack of time (2), and personal/health problems not related to the trial (1). As such, 30 participants completed the intervention and were included in the analyses (slow: n = 14; rapid: n = 16). As mentioned previously, the macronutrient prescription was individualised during the intervention. However, the macronutrient distribution was not different between groups (data not shown).
Discussion
Only a handful of studies have evaluated the impact of different rates of weight loss on REE [10,11] and appetite ratings [3,10] and we are unaware of any study that investigated changes in EI, palatability and smell capacity under these conditions. To our knowledge, the present study is also the first one to investigate changes in REE and fasting appetite at multiple time points during the intervention in groups under different rates of weight loss who were prescribed the same total energy
Funding
Luzia Jaeger Hintze was supported by a scholarship from the National Council for Scientific and Technological Development (CNPq, Portuguese: Conselho Nacional de Desenvolvimento Científico e Tecnológico) and the Ontario Graduate Scholarship (OGS).
References (55)
- et al.
The effect of rate of weight loss on long-term weight management: a randomised controlled trial
Lancet Diabetes Endocrinol.
(2014) - et al.
Poststarvation hyperphagia and body fat overshooting in humans: a role for feedback signals from lean and fat tissues
Am. J. Clin. Nutr.
(1997) - et al.
Imposed rate and extent of weight loss in obese men and adaptive changes in resting and total energy expenditure
Metabolism
(2015) - et al.
Weight loss, Weight Maintenance, and Adaptive Thermogenesis
Am. J. Clin. Nutr.
(2013) - et al.
The assessment of binge eating severity among obese persons
Addict. Behav.
(1982) - et al.
A new indirect calorimeter is accurate and reliable for measuring basal energy expenditure, thermic effect of food and substrate oxidation in obese and healthy subjects
E. Spen. Eur. E. J. Clin. Nutr. Metab.
(2011) - et al.
Assessing validity and reliability of resting metabolic rate in six gas analysis systems
J. Am. Diet. Assoc.
(2009) - et al.
Appetite sensations and satiety quotient: predictors of energy intake and weight loss
Appetite
(2007) - et al.
A satiety quotient: a formulation to assess the satiating effect of food
(1997) Eta squared and partial eta squared as measures of effect size in educational research
Educ. Res. Rev.
(2011)