“Cardio is the best exercise for fat loss.”
Cardio takes off a little more fat than lifting alone, but the edge is small and doing both gets people leaner.
Cardio works for fat loss, so keep it if you like it. What it does not do is protect muscle when you eat less, and that is the job lifting does. The scale can hide this: it cannot tell fat lost from muscle lost, or fat lost from muscle gained.
If you only do cardio, add two lifting sessions a week. If you only lift, add some cardio you enjoy. Track your waist and strength along with the scale.
An 8-month randomized trial and a 15-trial meta-analysis both found cardio takes off only about 2.5 to 3 pounds more fat than lifting, and that doing both cardio and lifting gives the best body composition. The trials are short and the cardio-plus-lifting comparison rests on only a few of them, so the size of the edge could shift.
Cardio takes off a little more fat than lifting alone, but the edge is small and doing both gets people leaner. Across 15 trials, cardio took off only about 2.5 pounds more fat than lifting over a few months, so calling it the best overstates it. In an 8-month trial, the group doing both cardio and lifting lost the most fat on average (5.4 pounds) and had the biggest drop in body fat percentage and waist size. In the trials, the best results came from eating in a modest calorie deficit and doing both cardio and lifting, which kept more muscle than cardio alone while fat came off.
In the 8-month trial of 119 overweight adults who did not change their diet, the cardio was about 12 miles' worth a week on treadmills, elliptical trainers or exercise bikes at a fairly hard, steady pace. The cardio group lost 3.7 pounds of fat and the lifting group 0.6 pound. On the scale, cardio loses about 2.5 pounds more than lifting, partly because lifting adds muscle that the scale hides: the lifting group gained 2.4 pounds of muscle and weighed 1.8 pounds more at the end. Once people eat in a calorie deficit, the type of exercise stops mattering for weight. In a 6-month trial of 160 dieting older adults, the cardio, lifting, and cardio-plus-lifting groups lost about the same weight (about 20, 19 and 19 pounds) and about the same fat (about 14, 16 and 15 pounds). The difference was what they kept: the cardio-only group lost about 6 pounds of muscle and the lifters about 2 pounds, and hip bone density fell 3 percent with cardio alone versus 0.5 percent with lifting.
Exercise alone, with no change in eating, takes off about 3 to 8 pounds in trials of overweight adults, whatever the type. An analysis of 15 cardio trials found the main reasons the scale moves so little are that the prescribed exercise burns only a few hundred calories a few times a week, and that some of those calories get eaten back. In 13 of the 15 trials, the exercise deficit was smaller than a typical 500-calorie-a-day diet.
Can cardio alone get you leaner?
Yes. In the 8-month trial, cardio alone with no diet change took off 3.7 pounds of fat and about 0.4 inch of waist. It also roughly tied the cardio-plus-lifting group for fat lost, since the gap between them could have been chance. Adding lifting on top improved body fat percentage and waist size further, because muscle went up while fat went down.
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