Three recent fasting studies lend clarity to the timing of fasting for weight loss and benefits of fasting diets for breast cancer patients.
STUDY ONE/ A study, in Cell Metabolism, compared the timing of two daily fasting diets, also known as time-restricted feeding diets, for weight loss. The study, published by researchers from the University of Illinois at Chicago, compared a 4-hour time-restricted feeding diet and a 6-hour time-restricted feeding diet to a control group.
Participants in the 4-hour time-restricted feeding diet group were asked to eat only between the hours of 1 p.m. and 5 p.m. Participants in the 6-hour time-restricted feeding diet group were asked to eat only between the hours of 1 p.m. and 7 p.m.
In both the study groups, patients were allowed to eat whatever they wanted during the 4-hour or 6-hour eating period. During the fasting hours, participants were directed to only drink water or calorie-free beverages. In the control group, participants were directed to maintain their weight and not change their diet or physical activity levels. The participants were followed for 10 weeks as weight, insulin resistance, oxidative stress, blood pressure, LDL cholesterol, HDL cholesterol, triglycerides and inflammatory markers were tracked.
The study found the following:
- Participants in both daily fasting 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 researchers also found that insulin resistance and oxidative stress levels were reduced among participants in the study groups when compared with the control group.
- There was no effect on blood pressure, LDL cholesterol, HDL cholesterol or triglycerides.
- There also was no significant difference in weight loss or cardiometabolic risk factors between the 4-hour and 6-hour diet groups.
STUDIES TWO & THREE/ A University of Southern California-led team of scientists has found that a fasting-mimicking diet combined with hormone therapy has the potential to help treat breast cancer, according to published animal studies and small clinical trials in humans in the journal Nature and Nature Communications.
In studies on mice and in two small breast cancer clinical trials, researchers at USC and the IFOM Cancer Institute in Milan – in collaboration with the University of Genova – found that the fasting-mimicking diet reduces blood insulin, insulin-like growth factor 1 (IGF1) and leptin. In mice, these effects appear to increase the power of the cancer hormone drugs tamoxifen and fulvestrant and delay any resistance to them. The results from 36 women treated with the hormone therapy and fasting-mimicking diet are promising, but researchers say it is still too early to determine whether the effects will be confirmed in large-scale clinical trials.
References:
Cienfuegos S, Gabel K, Kalam F, et al. Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity [published online ahead of print, 2020 Jul 8]. Cell Metab. 2020 Caffa I, Spagnolo V, Vernieri C, et al. Fasting-mimicking diet and hormone therapy induce breast cancer regression. Nature. 2020;583(7817):620-624.
