| Summary: | Background and Aims. Dietary restriction in healthy adults has been shown to promote cardiometabolic health and autophagy; the degradation and recycling of damaged and dysfunctional cytoplasmic contents. Low protein diets may further stimulate autophagy through mTOR inhibition mediated by low amino acid availability. This project aims to investigate the effects of a 7-day nutritional intervention in healthy humans using very low-calorie (VLCD), fasting-mimicking plant-based diets with low and high protein content on cardiometabolic outcomes, body composition, molecular markers of autophagy and ER-stress, and gut microbiome health.
Methods. Forty five healthy males and females were randomly stratified to 1 of 3 groups: Control (Isoenergetic diet); Low Protein VLCD (850 Calories per day: 10% protein); High Protein VLCD (850 Calories per day: 30% protein). Participants provided fasted blood, urine, and stool samples, had a Dual Energy X-Ray Absorptiometry (DEXA) body composition scan, and underwent functional tests of cardiovascular health before and after the 7-day intervention, allowing a comparison of low and high dietary protein content on key outcomes.
Results. Both low and high protein VLCDs reduced fasting plasma glucose and IGF-1, and induced ketogenesis. The high protein diet did not appear to inhibit the induction of autophagy or promote excessive ER- stress responses at the molecular level. Both VLCD diets reduced body weight and fat mass, with low protein selectively reducing subcutaneous fat mass and high protein selectively reducing visceral fat mass. Lastly, gut microbiome diversity and circulating triglycerides and fatty acids were improved by the high protein VLCD only.
Conclusions. These findings expand previous work displaying the benefits of a low protein VLCD on cardiometabolic health and autophagy in healthy adults and provide novel potential benefits of a high protein VLCD that would allow tailoring it to an individual’s health needs and preferences.
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