She did the same thing you did. Same diet. Same rules. Same weekly check-ins with the same dietitian, in the same study, for the same twelve months. She lost 30 kg. You gained 10.
That's not a hypothetical. That's what Stanford found when they put 609 adults on either low-carb or low-fat for a full year. The $8.2 million DIETFITS trial wasn't small, wasn't short, and wasn't sloppy. Each group got 22 dietitian-led sessions. Same guidance. Same support. Same timeframe.
The question they wanted to answer: which diet wins?
The answer was stranger than either side expected.
After 12 months, the average difference between low-carb and low-fat was 0.7 kg. Not 7. Not 17. Less than a bag of apples. The gap was so small it wasn't even statistically significant — it could have been pure chance. The two most debated diets on earth, tested with $8.2 million and 609 people, produced effectively the same result.
But that wasn't the finding that changed everything.
Inside each diet group, individual results ranged from losing 30 kg to gaining 10 kg. Same diet. Same dietitian. Same twelve months. The person sitting next to you in that study lost a third of their body weight. The person next to them gained weight.
The gap between people was 40 kg. The gap between diets was 0.7 kg. That's a 57-to-1 ratio. The person you are mattered 57 times more than the plan you picked.
That number doesn't just mean low-carb and low-fat tied. It means the entire debate about which diet to follow has been arguing over the rounding error while ignoring the 40-kg variable standing right on the scale.
So maybe the answer is personalization. Maybe there's a test that matches you to your ideal diet. Your genes. Your insulin. Your body's specific blueprint.
Stanford tested that too. They tested the DNA of all 609 participants, looking for a genetic pattern linked to diet response. No match (P = 0.20). They measured each person's insulin response before the study started, the other leading candidate. No match either (P = 0.47). Both signals that were supposed to sort you into "keto person" or "low-fat person" came up empty.
$8.2 million. 609 people. A full year. And the two most promising personalization variables produced nothing. The sorting hat the DNA-diet industry sells for $200 is making a prediction Stanford couldn't make with 3,000 times the budget.
The gap between people was 40 kg. The gap between diets was 0.7 kg. That's a 57-to-1 ratio.
There's a detail buried in the data that makes this stranger. Neither group was told to count calories. Dietitians focused on food quality, not quantity. But when researchers measured what both groups actually ate, the numbers converged. Both groups reduced their intake by roughly 500 to 600 calories per day. The difference between them: 2.9 calories. Two different food philosophies. Same caloric landing zone. Without anyone telling them to get there.
Part of this study was funded by NuSI, a $40 million organization founded to prove that carbohydrates drive obesity. When the data showed no difference, NuSI attempted to interfere with the researchers. The organization built to settle the diet debate couldn't accept the answer their own funding produced.
If you've tried a diet that worked for someone you know and failed for you, the reflex is to blame the plan. Find the right one. Try hers. Match your genes.
The data points somewhere else. The 40-kg gap between people on the same plan was 57 times larger than the gap between plans. Nobody, not even Stanford with $8.2 million, has identified which personal variable explains who ends up on which end of that range.
The question was never which diet to follow. The question is what makes your body respond differently from hers on the exact same one. That question is still open, and some of the answers have nothing to do with what you eat and everything to do with when.