You cannot outrun a bad diet
Updated: Aug 6, 2020
It’s about time this myth is busted once and for all. You cannot outrun a bad diet!
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Humans have evolved to thrive on fairly small amounts of fuel. Our ancestors sometimes had to endure all day hunts just to get an elk back to the camp to be shared by everyone. Do you think there was an extra helping equaling 3,200 calories for each of the hunters when they got back to the camp? It seems that our ancestors had to endure much harder lives on much less food than we do. We’re Priuses. We do not really need that much fuel, even when we work hard.
We aren't our ancestors, and we do have grocery stories. And I think all in all, we are a better specimen of human today than the sinewy, near death look of the primal humans depicted in most images.
So let's look at diet and the role of exercise in weight loss. Essentially, both diet and exercise help create an energy deficit that is essential for weight loss. Diet is pretty much just math, but exercise has that added ramping up the calories you burn when you are no longer exercising. Which makes it so appealing for weight loss, and makes you think it is the better choice of the two. (It is the better choice, but not necessarily for weight loss.)
Also consider that there is a difference between “weight loss” and “fat loss.” When you create a calorie deficit through dieting alone, you can achieve weight loss. That weight can come from anywhere, bone, muscle, organ mass, whatever. Exercise (the right kind) can help your body choose the right tissue to burn (fat). Without exercise, you might burn through lean body tissues which will actually make your fat percentage increase while your weight decreases. What kind of exercise is best to protect your lean mass? Obviously I'm going to say strength training.
Weight resistance exercises, whether through body weight, free weights, machines or whatever, place a demand on your body to create more lean tissue (muscle, bone mass, etc.). Lean tissue, is a little more costly to both build and own, so your at-rest calorie burn is higher. That’s like passive calorie burn. But that’s not all.That’s not even the good stuff.
When you build muscle, you build ancillary lean tissues such as bone mass, organ density (organ tissues are muscles), etc., that support this new muscle tissue. When there is a calorie deficit, your body is "forced" to burn fat for fuel (oversimplification). You did just spend an awful lot of resources to create that extra mass, and It's easier to just burn fat. So muscle building exercise not only build lean mass, which is calorie burning, but the activity itself protects lean mass from converting to fuel, and so instead you have fat loss, not just weight loss.
So the role of exercise in weight loss is less about increasing calorie deficit than it is about protecting your lean, calorie burning mass.
All of that said, how many calories is that in total at the end of the day? In my experience, even clients who train really hard may have a hard time losing weight with exercise alone. In my experience, that's one of 3 reason: 1) It keeps them focused on food and they are snackier (and snacks are calorie dense); 2) There are not enough hours in a busy day to exercise all of the added calories away; 3) (Shout out to NOLA) Their exercise regime cannot keep pace with the extra glass(es) of wine they feel they deserve every night.
So if weight loss -- no, fat loss -- is your goal, yes, exercise, but also make smart food choices worthy of our evolutionary survival.