Calories in. Calories out. This simple idea is the crux of any weight-loss plan. To lose weight, you have make sure you spend more calories than you consume. Mostly this happens by eating healthy foods and working out.

But anyone who’s tried to lose weight and failed knows there is more to it than that.

A few recent studies have honed in on what the magic formula might be.

First, there can be such a thing as too much exercise. A recent review article from October looked at several exercise-related studies and concluded that the most effective regimes were those that included low levels of exercise. Another study from just a month before that determined that 30 minutes was the prime amount of time to exercise in order to lose weight.

The key factor here is appetite and energy. Too much exercise leads to such a large calorie deficit that your body wants to overcompensate by making you eat more. In addition, while 30 minutes of exercise can leave you energized, more than that can leave you exhausted, meaning that you move much less during the rest of your day.

Second, in addition to calories and energy, your appetite is affected by hormones, which in turn are affected by exercise.

A 2012 study found that women who were offered a buffet immediately after running actually ate much less than women who walked or sat. Here’s the twist though: Women who ran had higher levels of the hormone that causes hunger. But they didn’t overeat! The reason why is because exercise also stimulates hormones that make you feel full, which can override the hunger hormones.

Another interesting study from just a month ago found that, over the course of 12 weeks, exercise helped participants regulate their own eating habits and avoid over-eating. In this case, they split overweight volunteers into two groups. One group consumed low-calorie shakes and the other had high-calorie shakes. Both groups exercised and then were offered a buffet lunch. At first, the people that consumed the high-calorie shake ate more at the buffet. But after three months of exercise, the high-calorie shake volunteers ate less at the buffet. It seems that exercise can help your body determine how many calories have already been consumed and adjust its internal meter to reduce the calories consumed later.

Learn more about the best time to exercise and the ten-minute exercise regime that gets results!