|Alternate Day Fasting: Low fat Vs. High Fat|
As far back as the 1930’s, an American scientist found that drastically reducing the calories fed to mice helped them to live longer and be healthier. In more recent times, the same thing has been shown in a variety of life forms including fruit flies, roundworms and monkeys. The mechanism or mechanisms by which dietary restriction increases life span are unclear, but the effects of dietary restriction include reduced metabolic rate, reduced oxidative damage, altered neuroendocrine signaling, and improved insulin sensitivity. Although conclusive results are years away, many improvements in biomarkers of longevity, including reduced core temperature, resting metabolic rate (RMR), dehydroepiandrosterone sulfate, glucose, and insulin, have already been observed. Prolonged dietary restriction also alters the expression of many genes from skeletal muscle, brain, and liver, including genes encoding heat shock proteins and uncoupling proteins and genes involved in oxidative damage. The idea of severely restricting calories every other day – rather than every day – to improve health and life expectancy came in 2003 following laboratory research carried out at the National Institute on Ageing in America. After 20 weeks, mice who were allowed to eat as much as they wanted on one day but not fed the next day, lived longer and had lower levels of glucose and insulin and improved insulin sensitivity compared to mice that were allowed to eat freely all of the time. But more importantly, these levels matched or were even better than those of mice who ate 40 percent fewer calories than normal every day. The scientists involved in the study concluded that alternate day fasting was just as likely to improve health and life expectancy as a daily calorie restriction. Scientists have now examined if varying the effect of fats in the diets on days that you eat had any impact on fat loss.
Researchers examined how alternate-day fasting with either a high or low diet. After a 2-week weight maintenance period, 29 obese women, 25-65 years old were randomized to an 8-week alternate day fasting-high fat (45% fat) diet or an alternate day fasting-low fat (25% fat) diet with 25% energy intake on fast days and ad libitum intake on feed days. Body weight, BMI and waist circumference were assessed weekly and body composition was measured using dual x-ray absorptiometry (DXA). At the end of the study, body weight, BMI, fat mass, total cholesterol, LDL-C and triglyceride concentrations decreased in both groups. In The alternate day fasting-low fat group had an advantage in terms of fat loss with a slight advantage in terms of the particularly health-relevant reductions in waist circumference in response to the low fat alternate day fasting diet, but a significant advantage in terms of total fat loss for the high-fat alternate day fasting group. In the alternate day fasting-high fat group, FFA concentrations were positively correlated with waist circumference. If your considering an alternate day fasting diet for fat loss, but sure to consume a higher fat ratio on days you are eating.
Heilbronn LK, Ravussin E. Calorie restriction and aging: review of the literature and implications for studies in humans. Am J Clin Nutr 2003;78:361–9.
Lee CK, Klopp RG, Weindruch R, Prolla TA. Gene expression profile of aging and its retardation by caloric restriction. Science 1999;285:1390–3.
Lee CK, Weindruch R, Prolla TA. Gene-expression profile of the ageing brain in mice. Nat Genet 2000;25:294–7.
Cao SX, Dhahbi JM, Mote PL, Spindler SR. Genomic profiling of short- and long-term caloric restriction effects in the liver of aging mice. Proc Natl Acad Sci U S A 2001;98:10630–5.
Varady, Krista A., et al. “Effects of weight loss via high fat vs. low fat alternate day fasting diets on free fatty acid profiles.” Scientific Reports 5 (2015).