Starvation is normally associated with undernutrition in third world countries or economically deprived conditions. However there are many situations in the more affluent world which are essentially starvation conditions. The most obvious are the eating disorders anorexia nervosa, bulaemia, and prolonged or inappropriate dieting.
Other conditions include the malabsorption diseases such as coeliac disease, lactose intolerance, infections, diarrhoea, and cachexia in cancer.
Perhaps the most insidious is prolonged dieting for weight loss or control. In prolonged dieting, by reducing caloric intake the body has insufficient caloric intake to meet normal demands, and goes into starvation mode with the consequent reduction in BMR. This results in an even lower caloric intake being required for weight loss.
Exercise has long been held to be of major importance in a weight loss program because of the extra energy used by the body. However, the extra energy that is expended is not that great, and the reason that exercising appears to work as a weight loss aid in some people may well be for completely different reasons.
Exercise helps to maintain the BMR, thus helping to overcome one of the major problems with weight loss dieting. If done when the body is in a postabsorptive state, then the muscles will more likely use the stored fat deposits for energy rather than liver glycogen and circulating glucose; hence early morning pre-breakfast exercise is beneficial.
This needs to be combined with a diet which does not trigger the starvation response, but is not sufficient to replace any fat stores used in the exercise.