There are very few “laws” in physics. And Newton’s Four Laws of Thermodynamics are about a “proven” as science gets. As a big fan of science, I have to tell you that in Coach Stevo’s House, we obey the Laws of Thermodynamics. That’s because your body is a system like any other in that Newton describes in nature. A machine that takes in energy and performs work. It is a complicated machine with lots of moving parts, but the inputs and outputs are pretty simple. Food goes in; life comes out. And if you want to streamline your machine, you are going to have to obey the Laws of Thermodynamics. In very real terms, if you want to lose weight you are going to have to take in less than you put out because exercise is a dumb way to burn fat. Here’s why you can’t outrun a donut.

How You Work

You eat food. Food is made up of a lot of stuff, but the main components are carbohydrates (fast energy), fat (slow energy + some legos), protein (legos + some slow energy), and fiber (lubrication). Your body uses the energy you eat to manipulate the legos you eat into creating you while and the fiber keeps things from grinding to a halt. The unit of measurement of food energy is kcal (or just ‘calories’). Sometimes there’s not enough energy to make you, so your body has a backup system to store it when there’s too much. Biologists call that ‘adipose tissue’ and it contains about 9 kcal of energy per gram. You call it fat. There is debate about the amount of body fat that is considered ‘healthy,’ but I don’t think anyone is gonna pitch a hissy fit if I suggest that 14-17% body fat for men and 21-24% body fat for women is good target for long-term health. (Health aside, I think with the right amount of muscle, most men achieve ideal hotness at 12% and women at 19%. But that’s totally my opinion). The average American man is 191 lbs and carries around 21% of that in fat. The average American woman is 164 lbs and about 28% of that is fat. Oh, and as I’ve talked about before, your body can’t really store protein. If it needs legos to build stuff and you haven’t eaten any lately, it strips what it needs from your skeletal muscle.

Getting Rid of Fat

Let’s say the average American lady wants to get hot. For most women, part (part!) of hotness is getting close to 19% BF. Most women will look crazy hot higher than that, but let’s just use this hypothetical lady as an example. She basically has 60,225 kcal of “extra” fat on her. The only way fat comes off outside of a surgeon’s office is by eating less calories than you use. That’s thermodynamics and most people know it pretty instinctively. But most people are also really bad at math. Since this equation has two sides (input and output), many people assume that they can up the output to exceed the input (‘burn fat’ by exercising a bunch). And while this is technically true, it’s just not realistic because your body is REALLY good at efficiently moving around. In fact, the average American woman only burns about 100 kcal per mile of walking and only 124 kcal when running at a 10 minute per mile pace (which most women can’t even maintain for longer than a minute or so). Assuming this rate of efficiency would be constant and assuming her dietary input would be exactly the same, our hypothetical woman would need to walk 602 miles in order to lose that 14.74 lbs of fat. That’s the distance from San Francisco to Tijuana, Mexico. But it gets worse because all those assumptions are wrong. Your body gets really efficient at movements that it does a lot (it’s called the training effect and it’s the whole point of training). So the more you walk, the less calories you burn walking. The more your run, elliptical, kickbox, Bar Method, TaiBo, pilates, yoga, and CrossFit, the less calories you burn doing them. Your body is also really good at telling your brain that it’s hungry when you work out more so there’s very little chance your dietary input would remain constant unless you control it. So even if you made it to Tijuana, you’d probably still have a few more pounds to lose!

Fat Loss in the Real World

Strength and cardio training is really important for lots of health and hotness reasons, but quite frankly exercise has little to do with fat loss. In the real world it takes about 16 minutes of running to expend the energy equivalent of a Krispy Kreme donut that most people eat in less than 30 seconds. Translation: you can’t outrun a donut. The answer? Don’t eat the damn donut.

The smart path to fat loss is through your stomach. Find a nutrition plan that works best for you and stick to it. If you are a normal, healthy adult free of disease, I suggest starting with my “four mores.” But if you like paleo, do paleo. If you like slow carb, do slow carb. Atkins, South Beach, Intermittent Fasting, they will all probably work if you stick to them. Any diet that you can live with long enough to maintain a 3,500-7,000 kcal per week caloric deficit will probably provide stable fat loss for you in the long run. So if you want to lose fat, don’t sweat so much, listen to your body (and your doctor or Registered Dietitian) and find a nutrition plan that works for you.