The Western diet has broken the hormonal controls that regulate body weight. Understanding this requires understanding the two villains: fructose and oxidized polyunsaturated fats.

The Weight Regulatory System

The human body has a sophisticated system for regulating body weight. Leptin, produced by fat cells, signals the brain when fat stores are adequate. Insulin, produced by the pancreas, signals cells to take up glucose. Ghrelin, produced by the stomach, signals hunger. These hormones work together to maintain a stable body weight.

The Western diet disrupts all three systems:

  • Fructose causes leptin resistance: The brain stops receiving the "stop eating" signal
  • Fructose causes insulin resistance: The body requires more and more insulin to maintain normal blood glucose
  • High insulin causes fat storage: Elevated insulin locks the body in fat-storage mode

The Fructose Mechanism

Fructose is metabolized almost entirely in the liver. When the liver is overwhelmed with fructose, it:

  1. Converts excess fructose to fat (de novo lipogenesis)
  2. Exports fat as VLDL triglycerides, raising blood triglycerides
  3. Accumulates fat in the liver (non-alcoholic fatty liver disease)
  4. Becomes insulin resistant
  5. Causes systemic insulin resistance

The obesity epidemic began in the 1970s — precisely when high-fructose corn syrup was introduced into the food supply and dietary guidelines shifted to low-fat, high-carbohydrate diets.

The Polyunsaturated Fat Problem

Industrial seed oils (soybean, corn, canola, sunflower) are high in polyunsaturated fatty acids (PUFAs), particularly omega-6 linoleic acid. These fats are highly susceptible to oxidation — both during cooking and within cell membranes.

Oxidized PUFAs:

  • Damage cell membrane function
  • Cause mitochondrial dysfunction
  • Promote inflammation
  • Impair insulin signaling

The Solution

The solution is to eliminate the two villains:

  1. Eliminate fructose (sugar, HFCS, fruit juice)
  2. Eliminate industrial seed oils (replace with butter, olive oil, coconut oil)

Replace with: whole foods, animal proteins, non-starchy vegetables, and healthy fats. This is essentially the diet humans ate for 99% of evolutionary history.