Keto vs low-carb: what's the actual difference?

Keto is a low-carb diet taken far enough to change which fuel your body runs on. "Low-carb" is everything from that point up to roughly half a normal carbohydrate intake. The line between them is not a brand or a food list — it is the point where your liver runs short of stored carbohydrate and starts producing ketones in quantity. In practice that means staying under about 50 g of carbohydrate a day, and most people hit it reliably at 20–30 g of net carbs. Eat 80 g a day and you are genuinely low-carb, getting most of what people come for, and not in ketosis. Both work. They work differently, and the clearest difference is hunger.

Where the line actually is

Your liver holds roughly 100 g of glycogen — a stored-carbohydrate buffer it drip-feeds into the blood between meals to keep glucose steady. Eat enough carbohydrate and that buffer is topped up all day, so the liver never has to look for another way to fuel your brain.

Cut carbohydrate below what refills it and two things happen together. Insulin settles to a low baseline, and low insulin is the permission slip for fat to leave fat tissue, so fatty acids arrive at the liver in much larger amounts. The liver converts some of them into ketones — mainly beta-hydroxybutyrate — which the brain can use in place of glucose. The conventional cut-off for "nutritional ketosis" is 0.5 mmol/L of beta-hydroxybutyrate in blood, and that is the only real definition of keto there is. Everything else is a food list someone wrote around it.

That is why the threshold is a range rather than a number: it depends on your size, your muscle mass, how much you move, and how depleted you already are. Someone lifting four times a week burns through glycogen and can sit in ketosis at 50 g. Someone sedentary may need 20 g.

The bands, in plain numbers

Those are conventions, not laws of nature, and the gaps between them are soft. The useful thing is knowing which one you are actually eating, which is easier than it sounds once you know whether to count total or net carbs — the net carbs guide covers that properly.

Why it matters for hunger

This is the part that decides whether a diet lasts. A meal with a meaningful amount of carbohydrate raises blood glucose, insulin rises to clear it, glucose comes back down, and as it falls you get hungry again — not because you are short of energy, but because insulin is still elevated enough to keep fat locked in storage. You have plenty of fuel on your body and limited access to it. That is the three-o'clock snack drawer, and it is a signalling problem rather than a willpower problem.

Below the ketosis line, that cycle mostly stops. Insulin stays at a low baseline, fatty acids flow out of storage continuously, and the brain has ketones available as a second fuel. The gap between meals stops being a fuel gap. Most people describe this as not thinking about food for hours, and it is the single most reported effect of crossing into ketosis.

At 80–100 g a day you get a muted version of the same thing: far flatter blood sugar than a standard diet, much less of the post-lunch crash, but the fuel switch is not thrown. For some people that is plenty. For anyone whose main problem is constant snacking, the stricter side does more work for you.

What is identical either way

• Protein. The target does not change with carbs — see how much protein.
• Salt. Lower insulin makes the kidneys excrete more sodium at any carb level, and that is what the keto flu guide is about. Under 50 g it is unavoidable; at 100 g it is milder but still real.
• Food quality. Meat, eggs, fish, vegetables and dairy are the base of both. Keto removes more of the fruit, root vegetables and legumes.
• Calories. Fat loss still needs a deficit. Ketosis makes a deficit easier to hold; it does not create one.

How to pick a track

Pick keto, or the ketovore and carnivore versions of it, if appetite is your main obstacle, if you want steady energy with no afternoon dip, or if you have tried moderation and it does not hold. The keto recipes here all sit at or under 8 g of net carbs a serving, so three meals land you inside the band without arithmetic.

Pick moderate low-carb if you play a hard, repeated-sprint sport, if you are already lean and training heavily, or if the social cost of eating strictly is the thing that has broken every previous attempt. A diet you keep beats a stricter one you quit in March.

And treat it as a dial, not an identity. Starting at 20 g for a few weeks and then easing up to 60 is a perfectly sensible plan; so is the reverse.

None of this is medical advice. If you take medication for diabetes, blood pressure or a kidney condition, talk to your doctor before you cut carbohydrate much — those doses are often set against your current diet and may need adjusting, which is their call, not yours and not ours. Don't stop anything on your own.

The app counts net carbs per meal and shows the running daily total, so you can see which band you actually ate rather than which one you meant to — start free.