Keto made easy

Does Insulin Make You Fat?

Quick answer: Not on its own. Insulin is the hormone that tells your body to store energy and holds back fat breakdown, and high insulin is tied to hunger and to blood-sugar problems. But when researchers controlled every meal, the low-fat diet lost more body fat than the low-carb one, so insulin doesn't override calories. On keto, lower insulin earns its keep by making a calorie deficit easier to live with.

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The myth

The strong version goes: carbs raise insulin, insulin stores fat, so carbs make you fat and calories don't matter. Cut carbs, keep insulin low, and fat melts off no matter how much you eat.

It's a tidy story with a real mechanism inside it. The problem is the last step.

What insulin actually does

Insulin is a storage signal. When it's high, your body files energy away and holds back on releasing stored fat. When it's low, the liver is free to break down fat and build ketones; ketogenesis is regulated by insulin and glucagon (StatPearls, Ketogenesis).

KetoDick teaches the same chain. Insulin impedes lipase, the enzyme he says breaks fat down, and chronically high insulin is linked to insulin resistance, pre-diabetes and type 2 (video s_sNd1v8Low). His takeaway: high insulin makes stored fat hard to get at, which is why a heavier person can be hungry while carrying plenty of energy (videos s_sNd1v8Low, 9AGpKAfs3Yk).

That part is the reason keto feels different. The question is whether it changes how much fat you lose for the same amount of food.

The test: same food budget, different insulin

The cleanest test is a metabolic ward, where people live in the unit and every meal is controlled.

In one ward study, 19 adults were put on a carbohydrate-restricted diet and a fat-restricted diet. The carb-restricted diet is the one built to keep insulin down. Body-fat loss was 53 grams a day on carb restriction and 89 grams a day on fat restriction (Hall et al., 2015). The diet with more insulin lost more fat.

In another, 17 men switched to a ketogenic diet at the same calories. Energy expenditure rose by about 57 kcal a day, and body-fat loss slowed after the switch (Hall et al., 2016).

Out in the real world, DIETFITS randomised 609 adults to healthy low-fat or healthy low-carb for a year. They lost 5.3 and 6.0 kg, not significantly different, and how much insulin people secreted didn't change which diet worked better for them (Gardner et al., 2018). If insulin were the master switch, the high-insulin people should have done much better on low-carb. They didn't.

Where insulin really matters

None of that makes insulin irrelevant. It just puts it in the right job.

So what you do is stop thinking of insulin as the thing that makes you fat, and start thinking of it as the thing that makes eating less hard or easy. Keep carbs low, let hunger come down, and the deficit gets a lot less miserable.

What the research says

The ward studies were short and small, and the 2016 one enrolled only men. They answer the "same calories" question well; they don't capture months of free-living appetite.

KetoDick's take

His position is that insulin is the lever for hunger and fat access, and that's why keto works: it lets people eat less comfortably (videos 9AGpKAfs3Yk, s_sNd1v8Low). He says high insulin impedes lipase and access to fat stores, and that heavier people tend to produce more insulin (video cTGYIFOTPl8).

He also stops short of the strong myth. He accepts that "calories in, calories out" is mostly true (video 9AGpKAfs3Yk), and says calories still matter on keto (video 8Jk5ShSUpFY). In his long beginners' video he says insulin seems to be a factor in appetite but that he won't stretch it further than the research goes (video cTGYIFOTPl8).

Where his framing and the ward data differ, say both plainly. He describes high insulin as a block on getting at stored fat. In the ward, at controlled intakes, the higher-insulin diet still lost more fat. Both can hold if insulin's main effect in daily life runs through hunger, which is the part he leans on.

When to involve your doctor

If you use insulin or another medication that lowers blood sugar, cutting carbs can drop your glucose quickly. In the Virta clinic study, HbA1c fell from 7.6% to 6.3% and the intervention group used less diabetes medication (Hallberg et al., 2018). That's a dosing change your doctor needs to make with you, before or as you start, not after a low.

Key takeaways