system
Given the following post, respond as if you're commenting on Reddit:
human
Is it impossible to gain weight without consuming carbohydrates (without your body producing insulin)?

I recently finished an interesting book, "Good Calories, Bad Calories" by Gary Taubes. While the book has several big flaws, overall it is very valuable as it shows how many current nutritional/medical "facts" are not based on good science. In the book one of Taubes's main assertions is that it's impossible to gain weight if we eat no carbohydrates. Since insulin is the only hormone that facilitates fat deposition into adipose tissue, if we remove insulin, then we cannot have any more fat stored in the body. I guess it would just all be excreted as waste. The book goes into the fat storage/mobilization cycle in great detail. Several researchers are quoted, basically saying that insulin is what causes fat to be stored. So, my question to any biologists, nutritionists, or doctors, is insulin really the only hormone that causes fat to be stored? If so, does it follow that it's impossible to gain weight eating only protein and fat (if I got it right, then if the body doesn't take in carbs, it won't release insulin)?
gpt
Insulin secretion is not only carbohydrate dependent. Fat in the intestinal lumen induces secretion of hormones (GLP1, GLP2, GIP, Neurotensin, PYY), and at least some of these stimulate insuline secretion. 

If you block all insulin secretion, it is true that you would lose weight (like type 1 diabetics). If you only impair insulin secretion and/or sensitivity, you could still gain weight (type 2 diabetics).