The multi-faceted process of aging encompasses various human pathologies such as diabetes, hypertension, neurological and cardiovascular diseases and cancer among many others. The hallmarks of aging has broadened the scope of eligible interventions aimed at delaying aging. Among the scores of anti-aging strategies, dietary restriction (DR) intervention has opened gamut of physiological benefits for humans. In this review, we elucidate briefly the two strict DR approaches practiced among humans especially for weight loss, but additionally for its metabolic benefits and lifespan elongating effects. Calorie restriction has been tried in diverse model organisms including humans, but CR has been challenging for humans due to its adverse effect. We discuss the metabolic pathways operating in case of intermittent fasting (IF) and calorie restriction (CR). Lastly we review a vital mechanism observed during fasting, ketogenesis, and scrutinize the latest emerging dieting trend keto diet with reference to IF.