Why Keto Works: The Advantage Is Adherence, Not a Metabolic Trick
In this video
A four-minute argument with one thesis: the "secret" of keto is that people can stay on it.
- [0:00] People credit a metabolic advantage, or ketosis itself. My answer was diet adherence.
- [0:30] Calories in, calories out and "eat less, move more" are mostly true. The real question is how to do that without being hungry and feeling terrible.
- [1:00] Cutting carbs lowers insulin, which I called one of the main hormonal drivers of hunger. So the diet doesn't run on willpower.
- [1:30] Month one: restrict carbs, but eat whatever amount you want. Calorie restriction comes later, in the weight-loss phase.
- [2:30] Everybody knows you lose weight by eating less. The question is how to lose weight comfortably, and my answer was control insulin through carbs.
- [3:00] Protein tops out, which I put at about 800 to 1,000 calories a day for an adult male. Carbs give maybe 80. So the rest has to come from fat.
- [3:30] High insulin gets in the way of lipase and access to fat stores. Ketosis gives steady energy and ends the hunger-crash cycle.
Watching this in 2026
Of everything from 2017, this thesis has held up best. I conceded the physics up front, calories in and calories out, and put keto's value in how it feels to eat less. That framing does not depend on any special fat-burning claim, which is good, because the ward studies didn't find one.
The mechanism half is where I'd be more careful now. I stated insulin → lipase → hunger as fact. It's a reasonable story, and it's the one I told across the channel (videos 9AGpKAfs3Yk, UygKGoP_BtA). But it's a story about why. The trials only measure what happened.
The claim worth unpacking: is there a metabolic advantage?
I said the secret wasn't metabolic advantage. The metabolic-ward data agree.
- Hall et al., 2016: 17 men moved to a ketogenic diet at the same calories. Energy expenditure went up 57 kcal a day, and body-fat loss slowed after the switch.
- Hall et al., 2015: with calories cut equally, 19 adults lost 53 ± 6 g of body fat a day on carb restriction and 89 ± 6 g a day on fat restriction.
So at equal intake, keto isn't a fat-loss shortcut. What's left is intake, which is the adherence argument.
The free-living trials show the adherence problem too. In Foster et al., 2003, 63 adults on low-carb lost more at 3 and 6 months, but the gap wasn't significant at 12 months, and retention was low in both groups. Adherence is the hard part on every diet, keto included.
On the insulin link: the evidence pages do confirm that insulin and glucagon regulate ketone production in the liver (StatPearls, Biochemistry, Ketogenesis). They don't include a trial testing insulin → hunger directly. Treat that part as my explanation, not as a measured result.
The line that didn't hold up: the protein ceiling
"It can't be an extremely high protein diet," because around 800 to 1,000 calories of protein you "run out of the ability to even digest" more (from the video). I made the same argument in another video, with a 220 g (about 880 calories) protein limit (video cTGYIFOTPl8).
The research doesn't describe a digestive ceiling at that level. Trials have fed much more on purpose. In Longland et al., 2016, young men in a hard deficit ate 2.4 g per kg a day and gained lean mass. The ISSN position stand discusses intakes above 3.0 g per kg a day for resistance-trained people. Those are about muscle and body composition, not proof that any amount is ideal, but they aren't a hard wall either.
And protein matters for my own thesis. In Weigle et al., 2005, raising protein from 15% to 30% of energy, with carbs held constant, cut what 19 adults ate by 441 kcal a day, and they lost 4.9 kg over 12 weeks. If the goal is eating less comfortably, protein is one of the strongest levers there is. More in protein and satiety.
The figure was also a man's figure. Most people reading this are women, and your numbers will be lower.
Then vs now
Here I told month-one viewers to eat whatever amount they wanted. That stayed the month-one rule. What changed is how I talked about fat once hunger settles:
- July 2017: "push fat where you can" (video DoSUgIr2rNo).
- August 2017: "stop eating too much fat" (video NUJNFG6lLWw).
- 2018: fat is the variable you raise and lower by phase (video UygKGoP_BtA).
That arc fits this video's own logic. If fat is only "the rest" after protein and carbs, it's also the first thing to come down when you're not hungry.
Who should involve a doctor
If you take medicine for diabetes or blood pressure, talk to your doctor before cutting carbs hard. Your doses were set for the old way of eating. If you have kidney disease, check your protein target with your doctor rather than copying anyone's number, mine included.
Key points
- The video's thesis: keto works because people can stay on it, not because of a metabolic trick.
- Ward studies at equal calories found no extra fat loss on keto (Hall 2015, Hall 2016).
- Adherence fades on every diet (Foster 2003).
- Insulin → hunger is the explanation offered, not a measured result.
- The "protein ceiling" doesn't match the trials; higher protein reduced intake in Weigle 2005.
- Month one: cut carbs, eat to full. Fat comes down later.
Related
- Guide: insulin · hunger · keto vs low-fat · how much fat · protein and satiety · too much protein?
- Blog: the keto metabolic advantage · does insulin make you fat? · is keto sustainable? · does protein help weight loss? · is keto a high-fat diet? · eat fat to satiety
- Videos: do calories still matter? · stop eating too much fat · keto basics