One of the biggest problems nowadays is aging and the diseases it brings. In order to prolong and improve the quality of life there had been many experiments about influences various environmental factors have on prevention and slowing down the progression of various diseases. One environmental factor had caught the eye among scientists and it is diet which stands for the simplest intervention that might help. Thus, this paper is about effects diet has on human physiology and metabolism. There are several well-known diets which have shown the positive effects on physiology: caloric restriction (CR), time-restricted feeding (TRF), intermittent fasting (IF) and fasting-mimickig diets (FMDs). The first two diets, CR and TRF have been elaborated in this paper which shows researches that have been done by the present with people and animals as subjects. However, it is important to note the main problem investigating this topic is human factor and inconsistency in adhering to this diet for longer period of time. Research done about CR include some mechanisms explaining the effects it has on aging, tumorigenesis and angiogenesis, inflammatory process and obesity, diabetes and cardiovascular health. Despite a small number of reaserch published about TRF, it has been known that it has effect on cyrcadian rhythms, lipid factors, cardiovascular health and helps to reduce body weight.