Keto made easy

Does Being in Ketosis Mean You're Burning Body Fat?

Quick answer: It means you're burning fat, but not necessarily your fat. Your liver makes ketones from fatty acids, and those can come from the food you just ate as well as from your stores. If your diet is heavy in butter, oil and cream, you can be in ketosis all day and not lose an ounce. Body fat comes off when you eat less energy than you use.

In this article

The myth: ketosis equals fat loss

You'll hear it everywhere: "once you're in ketosis, you're a fat-burning machine." It's half right, which is what makes it sticky.

Yes, in ketosis your body is running mostly on fat and ketones rather than glucose. No, that doesn't mean the fat being burned is coming off your body. The fuel switch and the fat loss are two different things, and the first doesn't guarantee the second.

Two places the fat can come from

Your liver makes ketones from fatty acids (StatPearls, Biochemistry, Ketogenesis). Your body has two places to get those fatty acids:

Source Example Effect on body fat
Fat you eat Butter, oil, cream, fatty cuts Used first; any surplus can be stored
Fat you've stored Hips, belly, thighs Drawn down only when food doesn't cover your needs

Think of it like a household budget. Ketosis tells you you're paying in a particular currency. It doesn't tell you whether you're spending from this month's paycheck or your savings. If the paycheck covers everything, the savings don't move.

So what you do is stop treating ketosis as proof of progress, and start treating the fat on your plate as the thing you adjust.

The butter-coffee arithmetic

This is where most stalls hide. KetoDick ran the numbers on bulletproof coffee: a 400 to 500 calorie cup on a 1,300 calorie plan is about 40% of the day's energy (video cTGYIFOTPl8). That's a lot of food with very little in it besides fat.

He's careful to say bulletproof coffee isn't required for keto (video DLRlphyc1t8). Drink it if you enjoy it. His concern, for people eating keto to lose weight, is that it's a lot of fat with little accompanying nutrition. He'd rather you get fat from foods like salmon, avocado or chuck roast.

He has a similar worry about fat bombs: empty calories from coconut oil, butter and cream cheese (video cTGYIFOTPl8). Both keep you in ketosis. Neither draws on your stores while it's covering your energy needs. More in fat bombs and weight loss and the guide on bulletproof coffee.

When ketosis does help fat loss

None of this means ketosis is useless for weight loss. KetoDick's case is that it helps indirectly, through appetite.

His phase model goes like this (video NUJNFG6lLWw):

  1. Introductory phase. Roughly 2 to 4 weeks for thinner people and 4 to 8 for heavier people. Glycogen is gone but your body can't use its own fat well yet. Fat can be fairly unlimited here, to manage hunger.
  2. Weight-loss phase. Hunger self-regulates and you eat less without forcing it. Now the energy gap is filled from body fat.
  3. Maintenance. Dietary fat comes back up, because there's no longer a gap to fill from stores.

Notice that the fat on your plate goes high, then low, then high again. That's the whole point. In the weight-loss phase, if you're past week five, not hungry, and stalled, he suggests trimming about 20 grams of fat a day (about 180 calories) or 30 grams (about 270) (video NUJNFG6lLWw).

And his line on why you're in ketosis at all: eating fat doesn't "fire up" ketosis. Restricting carbs does (video NUJNFG6lLWw). So cutting a little fat won't knock you out of it. See should you eat less fat to lose weight on keto?

What the research says

Two metabolic ward studies, where researchers control every bite, speak directly to this.

In one, 17 men moved from a high-carb diet to a ketogenic one with the same calories. They were in ketosis, and energy expenditure rose by about 57 calories a day. But body-fat loss slowed after the switch (Hall et al. 2016). Being in ketosis didn't make them lose body fat faster.

In the other, 19 adults cut the same number of calories either from carbs or from fat. Body-fat loss was 53 ± 6 grams a day with carbohydrate restriction and 89 ± 6 grams a day with fat restriction (Hall et al. 2015). The low-carb arm was the one closer to keto. The low-fat arm lost more fat from their bodies. That's the myth and the reality side by side: running on fat and losing body fat are not the same measurement.

For the broader physiology, Puchalska and Crawford's review covers how ketones are made, used and signal in the body (Puchalska & Crawford 2017).

One caveat. The Hall studies were short and small, done in a ward, and held calories fixed. They can't test the thing KetoDick cares most about: whether keto makes it easier to eat less in real life.

KetoDick's take

He agrees with the core point and says it more bluntly: in the weight-loss phase you don't need to push the fats, so cut them back (video NUJNFG6lLWw). Calories still matter on keto, even if counting them may not (video 8Jk5ShSUpFY).

Where he adds something the ward studies can't show is the order of operations. He thinks telling a month-one person to cut fat or calories is "kind of cruel," from the video; they'll feel fatigued (video NUJNFG6lLWw). Eat to fullness first, let hunger settle, then let fat come down. His bet is that keto earns its place by making the deficit comfortable, not by burning more fat calorie for calorie. The ward studies don't contradict that; they just don't test it.

Key takeaways