Food Intake, Life Style, Aging and Human Longevity

Abstract

Many human beings are now overeating and becoming overweight. Long-term studies in the laboratory rat show that 40% food or calorie restriction (CR) without malnutrition retards primary aging, delays the onset of age-related diseases and extends life by 20–50%. No life-long CR-survival studies exist in humans. However, Okinawans on 40% CR for half their adult life live 4 years longer than Americans. Overeating leading to obesity in middle age reduces life expectancy by up to 13 years. Overweight increases mortality from cardiovascular disease, diabetes and cancer. There is no doubt that reducing food intake by 20% over 6 years in healthy middle-aged subjects reduces the risk factors for cardiovascular disease and diabetes. Several studies have shown that low levels of cardiovascular and diabetic risk factors in middle age increase life expectancy by 5–10 years. An alternative to CR is a healthy lifestyle of consuming a prudent diet (high in fruit, vegetables, whole grains and fish), maintaining a normal body weight, performing daily physical exercise and not smoking which leads to a 55% reduction in all-cause mortality over 24 years. During the twentieth century life expectancy at birth in developed countries increased by 28 years due mainly to medical advances in reducing infant, maternal and later-life mortality, plus better nutrition. Thus life extension was not secondary to reduced food intake, which actually increased leading to overweight and obesity in about 50% of adults by early twenty first century. On present evidence it is likely that long-term CR with a healthy lifestyle to prevent overweight and obesity would add only about 5–10 years to human survival. Food restriction is not recommended in old age.