In Good Calories Bad Calories, Gary Taubes wrote the somewhat shockingly definitive summary paragraph below (I've separated out the numbered statements for clarity):
By the mid-1960s, four facts had been established beyond reasonable doubt:(1) carbohydrates are singularly responsible for prompting insulin secretion;(2) insulin is singularly responsible for inducing fat accumulation;(3) dietary carbohydrates are required for excess fat accumulation; and(4) both Type 2 diabetics and the obese have abnormally elevated levels of circulating insulin and a “greatly exaggerated” insulin response to carbohydrates in the diet, ... (Kindle Locations 8010-8014)