The high rate of obesity has become a growing problem in the modern world. Obesity is associated with the incidence of several comorbidities, such as cardiovascular disease and type 2 diabetes. Although weight loss is considered the most important remedy for obesity, long-term weight maintenance is also important.
Study: High versus moderate protein intake reduces adaptive thermogenesis and induces negative energy balance during long-term weight loss maintenance in participants with prediabetes in the postobese state: a preview study. Image Credit: margouillat photo/Shutterstock
Metabolic adaptation, i.e. adaptive thermogenesis (AT), may be the key factor preventing the maintenance of long-term weight loss. TA causes a decrease in energy expenditure, which is significantly greater than predictions based on reductions in fat mass (FM) or lean mass (FFM).
Energy expenditure adaptations have been found to last for multiple years following a bout of weight loss. Therefore, after weight loss, a reduction in AT is extremely important for maintaining long-term weight loss. Some factors have been identified to reduce AT, such as physical activity, cold-induced brown adipose tissue activation, tea catechins, and capsaicinoids. Furthermore, high protein intake (HP) has also been linked to reduced AT after weight loss.
Interestingly, an HP diet leads to an increase in FFM, resting energy expenditure (REE), diet-induced energy expenditure (DEE), and total energy expenditure (TEE). The combination of increased physical activity and an HP diet is able to preserve REE despite a reduction in FM and FFM. Compared with a low-protein diet in weight-stable subjects, a twelve-week HP diet was observed to maintain sleep metabolic rate (SMR), TEE, and DEE. However, it is imperative to understand whether the post-weight loss HP diet counteracts TA.
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A recent Journal of Nutrition This study investigated whether the HP diet could reduce AT and expected positive energy balance (EB) during weight maintenance after weight loss in prediabetic patients in their post-obese phase. This research is part of diabetes prevention through lifestyle interventions and population studies in Europe and worldwide (PREVIEW).
The PREVIEW study is associated with three years of intervention for weight loss and maintenance in four intervention groups. These groups differ in the dietary component, i.e. HP (low glycemic index) and moderate protein (MP) (modest glycemic index) diet and physical activity. This study aimed to understand the manifestation of type 2 diabetes after three years of interventions. In addition, changes in body weight, insulin resistance and body composition were analysed.
The current study compared the effects of a controlled HP diet with an MP diet on EB and AT. This evaluation was conducted after completion of the PREVIEW study using a fully controlled breathing chamber. A controlled HP diet has been hypothesized to stabilize TA and increase energy expenditure.
A total of 38 participants were recruited to analyze the impact of two diets (HP and MP), differing in protein/carbohydrate ratio, on energy expenditure and respiratory quotient (RQ). A total of 20 individuals (males-7, females-13), with a mean age of 64, consumed the HP diet and 18 individuals (males-9, females-9), with a mean age of 65, consumed a MP diet. Lean mass and fat mass were used to calculate predicted resting energy expenditure (REE).
The various levels of macronutrient composition in the HP and MP diets resulted in the different balance of proteins and carbohydrates between the two groups. In the HP group, protein intake and oxidation were higher, which caused a more positive protein balance than in the MP group. However, compared to the MP group, carbohydrate balance was less positive in the HP group due to lower carbohydrate intake and oxidation.
Interestingly, a lower fat balance was observed in the HP group than in the MP group. No significant differences in BMI, FFM, FM, energy intake, energy expenditure, or body fat percentage were observed between the two groups. Based on energy expenditure, a 48-h HP diet induced negative EB and elevated REE, which were absent in the MP group.
Notably, the HP diet counteracted AT during weight maintenance after weight loss; however, the MP diet improved fat oxidation. In the HP group, lower EB related to MP was found, which was linked to reduced AT in the HP group.
Consistent with previous studies, the current study revealed the presence of AT up to 34 months after an 8-week weight loss period. During this time, the participants experienced an approximately 11.9 percent reduction in their body weight. EB was positively correlated with RQ.
The current study revealed that compared with the MP diet, the HP diet led to negative EB, which counteracted the AT for approximately 34 months after weight loss in prediabetic individuals during the post-obese state. The study’s finding underscores the importance of adhering to a diet with an increased protein to carbohydrate ratio for an extended period to maintain weight after weight loss.