Thread by @TamarHaspel

Let’s talk about low-carb diets! The skinny on them is that they work (in part) because restricting carbs, especially refined ones, controls hunger. But does it? There’s a ton of evidence about that. Let’s look at it! Here's the theory.
mayoclinic.org/healthy-lifest…

The idea is that carbs, especially refined ones, drive the release of insulin, which clears the bloodstream of glucose. When blood sugar drops, you get hungry. Therefore, refined carbs make you hungry, and you overeat.

https://twitter.com/davidludwigmd/status/1067605736845451264

The Glycemic Index (GI) measures how quickly your body turns food into sugar. High-GI = quick, low-GI = slow. But here’s the question: does that actually correlate with hunger? Here are some of the studies.

A low-GI breakfast decreased insulin response, but difference in satiety was not signficant.
sciencedirect.com/science/articl…

A meta-analysis of the effect of breakfast’s GI on subsequent intake found none.
ncbi.nlm.nih.gov/pmc/articles/P…

Glycemic response is unrelated to appetiite
ncbi.nlm.nih.gov/pubmed/17158418

Sometimes, a low-GI meal suppresses hunger better than a high-GI meal.
sciencedirect.com/science/articl…

But sometimes, a high-GI meal suppresses hunger better than a low-GI meal.
ncbi.nlm.nih.gov/pubmed/25733632

Feelings of fullness were “slightly higher” in the low-GI group, but subsequent intake was the same.
ncbi.nlm.nih.gov/pubmed/21775528

And another, with some signs that low-GI had increased satiety, but subsequent intake was the same.
ncbi.nlm.nih.gov/pubmed/12612226

An attempt to suss out whether GI is linked to appetite found that … it’s complicated and unclear. If you want to believe, you can cherry-pick evidence. If you don’t, you can cherry-pick evidence for that too.
ncbi.nlm.nih.gov/pubmed/19602827

What does it mean when the body of evidence is equivocal? Probably that the carb/hunger relationship doesn’t matter very much. (I’ll add that there is evidence that a ketogenic diet can help with diabetes and metabolic disorders, which is great!) ncbi.nlm.nih.gov/pubmed/30128963

I’m old enough to remember when the “Satiety Index,” a measure of the appetite suppression power of foods, first came out in 1995. Most satiating food? Potatoes, the food the GI crowd loves to hate. (It’s one reason I’ve always defended them: washingtonpost.com/lifestyle/food…

But the thing about the Satiety Index list is that fat/protein/carb-heavy foods are all over the place! That perfect specimen of fat + refined carbs, the croissant, comes in dead last. High protein foods do well, but so do high carb foods. ernaehrungsdenkwerkstatt.de/fileadmin/user…

A “fullness factor” that takes into account calorie density, protein, fat, and fiber fits the data pretty well. But you know what doesn’t? The glycemic index. Also, the carb content.

If a low-carb diet works for you, yay! Keep doing it. Ditto a low-fat diet, or any diet at all that helps you eat sensibly and moderately. But the evidence doesn’t support the idea that low-carb diets suppress hunger. THE END.