 What is the effect of intermittent fasting in humans? Human studies pick from a smorgasbord of intermittent fasting diets, so it's hard to generalize. Intermittent fasting seems to reduce weight and improve the health of overweight and obese people, but it's not clear if that holds true for people who aren't overweight or obese. A different study found that eating one meal a day led to a reduction in fat mass, but it also an increase in blood pressure and LDL and HDL cholesterol.