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Calories In/Calories Out vs Carb Restriction – What Works Best?

There is a long-established truism that weight loss is all about “calories in, calories out,” and along with it the apparently unshakeable assumption that all calories are created equal.

It’s all bunk. Sheer bunk. But it’s bunk with so much weight of belief behind it that it’s very hard to shake people’s faith in it, even people who should know better.

We’re still bombarded with propaganda from the calorie police

One of their favorites is to tell us that low-carb diets only work because they “trick” you or “fool” you into eating fewer calories, by making you feel less hungry. I have actually read exactly that: “Oh, that diet just works by making you less hungry.” As if that were a bad thing.

If that were true, I’d be okay with it. I mean, I’d rather be tricked or fooled into eating fewer calories by reducing my appetite than try to muster up the willpower to tolerate being ravenous half the time. (

Oh, Lord, the memories. . . When I was in my mid-twenties, I worked at a health food store. Every day I’d buy my lunch from our cooler – a sandwich on whole grain bread, a bottle of juice, a piece of fruit or a whole grain, honey-sweetened cookie. Such a healthy lunch. By two o’clock I’d be starving, and I’d spend the afternoon chewing sugar-free gum and trying to ignore the fact that I was surrounded by food.

But it’s simply untrue

Repeated clinical tests demonstrate that simply cutting calories causes the metabolism to slow down. Unlike your car, which will happily run at sixty-miles-per until it sputters and dies for lack of fuel, your body is a complex living organism, with powerful homoeostatic mechanisms designed to keep you from starving to death. If you follow the common advice to just cut a hundred or two hundred calories per day, your body will simply burn a hundred or two hundred calories less per day – and you will have that much less energy. Cut 500 calories per day and soon you’ll wonder why your “healthy” diet makes you so darned tired.

Fascinatingly, clinical tests have repeatedly shown that what sort of calories you eat influences how many calories you burn. It’s common for people to scoff at this notion, to say that it somehow defies the laws of thermodynamics. And it would, if your body were a machine. But again, your body is a complex living organism, and your food powerfully influences your hormonal signaling – mostly notably, your levels of insulin, which tell your body to store fat, versus your levels of glucagon, which tell your body to release fat.

Going back to the 1950s, a couple of British researchers named Kekwick and Pawan put obese subjects on a very low-calorie diet – just 1,000 calories per day – but they varied the macronutrient composition of the diets. Some subjects got most of their calories from carbohydrate, some from protein, and some from fat. They discovered that even on such a low-calorie diet, the people eating mostly carbs lost little weight, but the people getting mostly fat lost weight rapidly and easily.

So, they tried feeding obese subjects 2,000 calories per day, which sounds a whole lot easier to live with, doesn’t it? They tried a 2,000 calorie “balanced” diet and found that their subjects didn’t lose weight. This will come as no surprise to those of you who have struggled to lose weight on 1,500 calories or even 1,200 calories per day. However, when Kekwick and Pawan kept the calorie count the same, but knocked out the carbs, their subjects lost weight easily. Indeed, they found that the average subject could eat 2,600 calories per day and lose weight, so long as they stuck to protein and fat.

In the 1960s, a doctor named Frederick Benoit, working at the Oakland Naval Hospital in California, tried a related experiment. He first put his subjects on a fast, what we could call the “no calorie” diet. If it’s all about calories in/calories out, this should have caused the quickest possible fat loss. It did not.

Oh, Benoit’s subjects lost weight, an average of 21 pounds in 10 days. Which sounds great, until you hear the rest: On average, only seven and a half pounds of that was body fat. The rest was water and muscle. Indeed, they lost twice as much muscle as fat. Bad ju-ju.

So then Benoit put his subjects on 1,000 calories per day – again, a very low calorie diet, but after that total fast thing it must have felt pretty good. But here’s the thing: Benoit gave them a very low carb, very high fat diet. And what happened?

In the ten-day trial the subjects lost twice as much fat as they had eating no calories at all, an average of fourteen pounds apiece, with only half a pound coming from muscle mass.

But all of this is practically ancient history. I mean, it was in the last millennium! Anything more recent? (‘Cause after all, we know how much the human body has changed in the past 70 years, right?)

How about this: In 2000, a study was done at Schneider’s Children’s Hospital in New Hyde Park, New York, regarding obese adolescents. The kids were split into two groups, one eating a low-fat/high-carb diet – you know, all those fruits and veggies and grains and beans – the other eating a low-carb diet which the researchers frankly admitted was high-fat. On average, the kids in the low-carb group ate 66 percent more calories per day than the low-fat group – a total of 1,860 calories per day, as compared with just 1,100 calories per day for the low-fat kids.

What happened? The low-carb kids lost twice as much weight as the low-fat kids. Lest you think this was at the expense of their overall health, they had a greater improvement in their triglycerides and HDL cholesterol, too.

In 2003, a study was presented to the American Association for the Study of Obesity regarding the effect of macronutrient balance on weight loss. Twenty-one subjects were divided into three groups. Two groups got the same number of calories – 1,500 per day for women, 1,800 per day for men – but with different macronutrient ratios. One group ate 55 percent carbohydrate, 15 percent protein, and 30 percent fat. The other group ate 5 percent carbohydrate, 15 percent protein, and 65 percent fat. The third group got the same macronutrient balance as the low-carb group, but 300 more calories per day. The study lasted for three months, and all meals were provided to the subjects in a restaurant setting, so the researchers weren’t relying on the subjects to accurately calculate and report their meals.

What happened? The low calorie, low-fat/high-carb group lost an average of 17 pounds apiece. The low calorie, low-carb/high-fat group lost an average of 23 pounds apiece, or 35% more than the low-fat/high-carb group while eating the same number of calories. That’s a substantial difference. But here’s the kicker: The low-carb/high-fat group who got the higher calorie diet lost an average of 20 pounds apiece – still better than 17% more than the low-fat/high-carb group who had eaten fewer calories.

Another trial from 2003, this one in The Journal of Clinical Endocrinology & Metabolism, put moderately obese women either on a calorie-controlled low-fat diet or a very low-carb diet – 20g or fewer – with no restriction on calories. After a two-week period, the low-carb group was allowed to increase their carb count to between 40g and 60g per day so long as they remained in ketosis. They all kept detailed food journals.

Both groups reported a drop in calorie intake of roughly 450 calories per day and caloric intake was similar, but the composition of those calories was very different.

What happened? “The amount of weight lost was significantly greater in the very low-carbohydrate group compared with the low-fat group”

A study published in the journal Nutrients in 2021 looked at a low-carb diet versus a “balanced Mediterranean diet” in morbidly obese individuals. Quote: “The average weight loss was 5%, being 58% greater in the low-carbohydrate-group than Mediterranean-group.”

Can you hear Dr. Atkins saying “I told you so” from the Great Beyond?

Calories Still Matter

Mind you, I don’t mean to imply that calories don’t matter at all. They do. You do have to run a caloric deficit for fat to be released from your storage depots. But what kind of calories you eat – fat, protein, or carbohydrate (or, for that matter, alcohol) will have a major impact on how readily your body releases that fat, and how much of it you burn.

But most people can eat somewhere around 2,000-2,700 calories per day and lose weight on a low-carb diet – and feel full, satisfied, and energetic into the bargain.

Which beats the heck out of subsisting on 80 calories at a time of yogurt and canned soup.

Let us know your thoughts in the comments below.

Until next time stay low-carb, happy, and healthy and go have some fun.

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