New research suggests that doing exercise in your “fat burning zone” will actually reduce the amount of fat that your body burns for the rest of that day. A new study in the Journal of Applied Physiology had participants do 1 hour of cycling at 55% of their aerobic capacity only to find that “24 h fat balance was significantly more positive on [the exercise day] compared to [the non-exercise day].”
Local fitness expert Josef Brandenburg says, “this is what I’ve been telling my clients for years – aerobic exercise makes you fatter.” Brandenburg hypothesizes that the body responds to exercise based on the type of fuel it uses.
In high intensity exercise like sprinting and weight lifting the primary fuel is carbohydrate. Your body responds to carb-dependent exercise by making it easier for your body to replace those carbs (increasing your insulin sensitivity)
With low-intensity, aerobic exercise – like that done in the study and during most people’s workouts – the primary fuel is fat. Brandenburg thinks that burning fat as the primary fuel during exercise is the signal to your body to become better at storing fat, hence the results of the study.
He says your body responds by doing the opposite. At the end of a resistance workout you are smaller and weaker than when you started it, but your body responds by doing the opposite – building you up in preparation for the next time it is stressed.
“Research in the International Journal of Sports Nutrition shows that resistance training shifts your body to burn more fat for the 24 hours after your workout unlike with aerobics. I think that since body-fat is fundamentally regulated by the hormone insulin, the intense, carb-dependent exercise like resistance training makes you burn fat all day long because it reduces your insulin levels and improves your carbohydrate metabolism,”
