Current research shows that consuming low-energy diets, caloric restriction, can significantly extend the life span of small species until recently most research has shown this with rats, mice, fish and flies. Only in the past few years studies have been done on humans with calorie restriction.
It’s speculated that the reduction in metabolic rate that occurs with restricting energy intake results in much lower production of free radicals which significantly reduces oxidative damage and can prolong life. Caloric restriction also causes marked improvements in insulin sensitivity and results in hormonal changes contributing to lower incidence of chronic diseases like heart disease and diabetes. Calorie restriction can also alter gene expression which can reduce the effects of aging and prevent diseases like cancer.
Some metabolic effects of calorie restriction in several human studies are:
- Decreased fat mass and lean body mass
- Decreased insulin levels and improved insulin sensitivity
- Decreased core body temperature and blood pressure
- Decreased LDL and total cholesterol and increased HDL cholesterol
- Decreased energy expenditure beyond that expected for weight loss
- Decreased oxidative stress, reduced levels of DNA damage
- Lower levels of chronic inflammation
- Protective changes in various hormone levels
Keep in mind that species that live longer with caloric restriction are fed highly nutritious foods. Unhealthful restriction like starvation, wasting and eating disorders don’t result in prolonged life.
The debate over whether calorie restriction in humans is effective or not will continue with more research. While these debates are going on, some people are challenging themselves to these low energy diets in hope they will live much longer and healthier lives!
Source: Thompson, Janice, Melinda Manore, and Linda A. Vaughan. The Science of Nutrition. San Francisco, CA: Pearson Benjamin Cummings, 2011. Print.