Hypocaloric Low‐Carbohydrate and Low‐Fat Diets with Fixed Protein Lead to Similar Health Outcomes in Obese Mice

Abstract

Objective: It is controversial whether low-carbohydrate diets are better suited for weight control and metabolic health than high-carbohydrate diets. This study examined whether these diets induce different improvements in body composition and glucose tolerance in obese mice during caloric restriction (CR). Methods: Male C57BL/6J mice were fed an obesogenic diet ad libitum for 18 weeks and then subjected to 6-week progressive CR of up to 40%, using either a low-fat or low-carbohydrate diet with equal protein content. Mice fed a regular chow diet ad libitum served as controls. Body mass, hindlimb muscle mass, fat mass, energy expenditure, and glucose tolerance were compared between the groups. Results: Initially low-fat and low-carbohydrate groups had similar body mass, which was 30% greater compared with controls. CR induced similar weight loss in low-fat and low-carbohydrate groups. This weight loss was mainly due to fat loss in both groups. Energy expenditure of freely moving mice did not differ between the groups. Glucose tolerance improved compared with the values before CR and in controls but did not differ between the diets. Conclusions: Dietary carbohydrate or fat content does not affect improvements in body composition and metabolic health in obese mice exposed to CR with fixed energy and protein intake.

Methionine restriction plus overload improves skeletal muscle and metabolic health in old mice on a high fat diet

“…as described in another study by our group 51 . Before being transferred to the metabolic cage, the body mass of the mouse was determined on a scale (440-45 N, Kern, Germany).…”

Caloric Restriction per se Rather Than Dietary Macronutrient Distribution Plays a Primary Role in Metabolic Health and Body Composition Improvements in Obese Mice

“…It might be expected that diets higher in carbohydrate content are better suited to promote glucose disposal and glucose tolerance. Nevertheless, our results show that caloric restriction-induced loss of body fat rather than macronutrient composition of diet is a major factor in improvements of glucose control [ 20 , 47 , 48 , 49 ]. Cholesterol reduction was also strongly correlated with weight loss and was greatest with the low-fat and high-protein diets in our study.…”

“…Glucose tolerance tests were carried out after overnight fasting during the sixth week of CR as described previously [ 20 ]. Briefly, blood glucose concentrations were measured in blood samples from the tail vein using glucometer (Glucocard X-mini plus GT-1960, Arkray, Japan) in awake mice before glucose injection (0 min) and following intraperitoneal injection of glucose solution (2 g glucose per kg of body weight) 15, 30, 60, 90 and 120 min after injection.…”

“…Metabolic cage (OxyletPro, Panlab Harvard Apparatus, Barcelona, Spain) was used to assess respiratory quotient, energy expenditure and motor activity of freely moving mice [ 20 ]. After an overnight fast each mouse was weighed (ABS 80-4, Kern, Balingen, Germany) and housed in metabolic cage of a standard size for 3-h measurements with ad libitum access to water and without food.…”

“…28-week-old obese mice were randomly assigned to one of three weight-matched CR groups (n = 16 each) with different macronutrient distribution of diets (%kcal from fat, carbohydrate, protein) as provided by a supplier (Table 1 20,20) or (3) high-protein diet, HPD (%kcal 30,35,35). During 6-week CR was gradually increased from 20% (1st week) to 30% (2-4th week) and 40% (5-6th week) of daily energy intake by calculating the daily food ration for each mouse after adjustment for caloric density of the diets (4.1, 5.2 and 4.3 kcal/g for LFD, LCD and HPD, respectively).…”