Effects of Intermittent Versus Continuous Energy Intakes on Insulin Sensitivity and Metabolic Risk in Women with Overweight

Abstract

Objective: This study aimed to compare intermittent fasting (IF) versus continuous energy intakes at 100% or 70% of calculated energy requirements on insulin sensitivity, cardiometabolic risk, body weight, and composition. Methods: Women with overweight (n = 88; 50 ± 1 years, BMI 32.3 ± 0.5 kg/m 2 ) were randomized to one of four diets (IF70, IF100, dietary restriction [DR70], or control) in a 2:2:2:1 ratio for 8 weeks. IF groups fasted for 24 hours after breakfast on three nonconsecutive days per week. All foods were provided and diets matched for macronutrient composition (35% fat, 15% protein, 50% carbohydrate). Insulin sensitivity by hyperinsulinemic-euglycemic clamp, weight, body composition, and plasma markers were assessed following a "fed" day (12-hour fast) and a 24-hour fast (IF only). Results: IF70 displayed greater reductions in weight, fat mass, total-and low-density lipoprotein cholesterol, and nonesterified fatty acids compared with DR70 and IF100 (all P ≤ 0.05). IF100 lost more weight and fat than control. However, fasting insulin was increased. There were no group differences in insulin sensitivity by clamp; however, a 24-hour fast transiently reduced insulin sensitivity. Conclusions: When prescribed at matched energy restriction, IF reduced weight and fat mass and improved total and low-density lipoprotein cholesterol more than DR. IF prescribed in energy balance did not improve health compared with other groups, despite modest weight loss.

Does the Energy Restriction Intermittent Fasting Diet Alleviate Metabolic Syndrome Biomarkers? A Randomized Controlled Trial

“…There has been limited research into IER in patients suffering from metabolic syndrome, and the majority concerns obesity or overweight subjects. According to a study in which there was intermittent fasting versus continuous energy intake at 100% or 70% of requirements on insulin sensitivity, cardiometabolic risk, and body composition in metabolic risk in women with overweight, a 70% energy restriction fasting diet displayed greater reductions in fat mass, weight, cholesterol, and LDL values compared with continuous 70% energy restriction or eucaloric fasting [ 31 ]. Chow et al (2019) investigated the effects of a 12-week time-restricted diet (ad libitum intake during an 8-h eating window) on body composition and metabolic measure in subjects who are overweight and obese.…”

“…It has been reported that this type of practice in intermittent fasting types is promising in terms of cardiometabolic health due to its compatibility with the human circadian rhythm [ 35 ]. The dual-energy X-ray absorptiometry method has been used in many studies investigating the effectiveness of intermittent fasting diets in body weight management [ 31 , 32 ]. In this study, the bioelectric impedance method was used.…”

“…The only difference between the two diet types is the limitation of 8 h of eating hours and 16 h of fasting. Previous research has shown that only a time-limited diet without calorie counting is also effective for weight management [ 31 ]. Both groups succeeded in meeting the recommended average intakes of fiber in 12 weeks (25 g/day for adults).…”

Differential Effects of Alternate‐Day Fasting Versus Daily Calorie Restriction on Insulin Resistance

“…Another form of dietary restriction that has gained attention in recent years is alternate‐day fasting (ADF) . ADF regimens generally consist of an ad libitum “feast day” alternated with a 25% energy intake “fast day.” Accumulating evidence has suggested that ADF and CR produce similar weight loss (6%‐8%) over 2 to 12 months in healthy adults with overweight and obesity . Research has also indicated that both diets are safe and well tolerated .…”

Mechanisms of Lifespan Regulation by Calorie Restriction and Intermittent Fasting in Model Organisms

“…Additionally, some studies have shown that IF can improve metabolic health and physiological function in humans. IF reduced fat mass, lean mass, and body weight in healthy humans and obese patients [33,[100][101][102][103][104]. Similarly, IF improved lipid and glucose metabolism, reduced inflammatory response, lowered blood pressure, and improved cardiovascular health [102,[105][106][107][108][109].…”