Sugar (sucrose)

Sucrose is a disaccharide composed of glucose and fructose that Ray Peat argued has been wrongly demonized as a cause of diabetes and obesity, when in fact it is polyunsaturated fats that are the primary drivers of metabolic dysfunction. 2 Peat traced the historical vilification of sugar to John Yudkin's version of the lipid theory of heart disease, which blamed the fructose component of sucrose for elevated blood lipids, a theory that grew into a "cult" despite a lack of causal evidence. 1 In contrast, Peat highlighted 19th-century physicians like William Budd and E. Kulz, who successfully treated wasting diabetics by adding large amounts of sucrose or fructose to the diet, observing that diabetics could assimilate fructose better than glucose and that it reduced glucose in the urine. 2

Peat emphasized that sucrose has a lower glycemic index than pure glucose or starch, meaning it is less disruptive to the pancreas and does not stimulate insulin as intensely. 3 The fructose half of the molecule is anti-stress and anti-insulin stimulating; it enters cells easily, promotes glycogen storage, and actually impedes the glucose component from overstimulating the pancreas. 2 This glycogen-stabilizing effect helps steady blood sugar over time, making a sugar-based diet "a little steadier" than a starch-based diet. 2 Peat noted that adding sugar to the diet can increase the metabolic rate by twenty percent, allowing for weight loss by increasing heat production, provided one avoids the polyunsaturated fats that suppress mitochondrial respiration and block sugar oxidation. 2

The true metabolic threat, according to Peat, is the Randall Cycle, where an excess of free fatty acids blocks the ability to metabolize sugar, leading to the oxidative stress and cellular damage characteristic of diabetes. 2 Free fatty acids suppress mitochondrial respiration, increase toxic free radical production, and the resulting lactic acid displaces carbon dioxide, making proteins more susceptible to oxidative damage—damage often misattributed to glycation by sugars but actually caused by reactive fragments of polyunsaturated fats. 2 Peat cited evidence that a deficiency of so-called "essential fatty acids" prevents toxin-induced and autoimmune diabetes, while sucrose itself stimulates the regeneration of pancreatic beta-cells and protects them from free fatty acid damage. 3 Even feeding enough sucrose to cause fat deposition in the liver can protect it from oxidative stress. 2

Peat distinguished the effects of sucrose from those of starch and glucose, particularly when combined with fats. In animal experiments, a 68% sucrose diet produced the least fat pad weight compared to diets with starch, fructose-glucose combinations, or fructose-starch mixtures, especially when corn oil was present. 10 He warned that the worst dietary combination is pure glucose (from white flour) fried in polyunsaturated oil, which blocks cellular glucose oxidation, whereas a protective combination is saturated fat with fruit-derived fructose, as in ice cream with fresh fruit. 12 Sucrose from fruit also arrives with potassium, magnesium, and flavonoids, minerals and anti-inflammatory factors that further support carbohydrate metabolism; potassium itself has an insulin-like action, helping cells take up glucose without requiring insulin secretion. 2

Topically, sugar demonstrates profound healing properties. The practice of treating deep wounds, including diabetic ulcers and post-surgical infections, with honey or granulated sugar eradicates bacterial infections better than some antiseptics and accelerates healing with minimal scarring by optimizing collagen synthesis and extracellular matrix communication. 2 Peat maintained that in every tissue, it is the failure to oxidize glucose—not glucose itself—that produces oxidative stress, and that the active thyroid hormone T3 protects the heart by supporting glucose oxidation, with T3 production depending largely on glucose availability. 2 If overall nutrition is good, Peat concluded, white sugar is safe, very low in allergens, and can lower cortisol under stress, making it a protective substance rather than a poison. 8