A study conducted by the University of Illinois Chicago (UIC) has found that fasting diet for weight loss on a daily basis is most effective. It helps people who don’t want to count calories and find other diets fatiguing. Two daily fasting diets, also known as time-restricted feeding diets, have been found most effective for this purpose. The study has been published in Cell Metabolism.
The clinical trial compared a 4-hour time-restricted feeding diet and a 6-hour time-restricted feeding diet to a control group and its effects on body weight and cardiometabolic risk factors. “This is the first human clinical trial to compare the two diets and their physical effects,” said Krista Varady, professor of nutrition at the UIC College of Applied Health Sciences an author of the study.
Participants were divided into two daily fasting groups – one in a 4-hour time-restricted feeding diet group who were asked to eat only between 1 pm to 5 pm and the other in a 6-hour diet group, allowed to eat only between the hours of 1 pm and 7 pm. This continued for a period of 10 weeks. While there were no restrictions on the kind and type of food for both the diet groups, no consumption of solid food was allowed in the fasting periods, and the participants were only permitted water or calorie-free beverages. In a separate control group, participants were directed to maintain their weight and not change their diet or physical activity levels.
The participants’ weight, insulin resistance, oxidative stress, blood pressure, LDL cholesterol, HDL cholesterol, triglycerides and inflammatory markers were closely tracked for the entire duration. The study found that participants in both groups reduced calorie intake by about 550 calories each day simply by adhering to the schedule and lost about 3% of their body weight. The study groups’ insulin resistance and oxidative stress levels were also lower as compared with the control group. There was no effect on blood pressure, LDL cholesterol, HDL cholesterol or triglycerides.
Neither did the researchers find a significant difference in weight loss or cardiometabolic risk factors between the 4-hour and 6-hour diet groups. “The findings of this study are promising and reiterate what other studies have shown – that fasting diets are a viable weight loss option for those people who do not want to count calories or find other diets to be fatiguing,” Varady said. “However, for people who fasted for a longer time, did not lose any additional amount of weight. For this, we need to conduct further studies that directly compare the two diets or determine the optimal time for fasting. Until then, the current studies show that the 6-hour fast would suit most people who want to pursue a daily fasting diet,” Varady added.
No major adverse health events amongst the study participants were also reported by Varady and her fellow researchers. Only mild adverse phenomena such as dizziness or headaches were experienced by some but were limited to the beginning of the trial.