What is required to scientifically prove something causes disease
- Exposure must precede disease (something can’t make you sick before you come in contact with it; fat can’t cause disease if disease came before the person was fat)
- Association between cause and effect must be strong (example: The association of BMI and cholesterol is only 0.1, which means that body weight explains only 1% of the variation in cholesterol levels between people.)
- Association must be consistent across studies
- Dose gradient must exist (as exposure is greater, effect should be greater; people with higher BMI should die more)
- Association should be biologically plausible
No random clinical trials show that losing weight decreases mortality.
A summary of some study findings
- A study of patients by age showed that death rates didn’t vary much by body size compared to death rates between patients of different ages; i.e., if you’re old, you’re seriously more likely to die (duh!)
- A study of hospital deaths shows that larger people are more likely to survive a hospital stay
- Body fat increases with age even when weight/BMI does not change; i.e., muscle tissue converts to fat as you age even if you don’t gain any weight
- The three top factors contributing to mortality, in order of importance: getting older (stop that right now or you’ll die!), smoking, and having previously smoked. These three things are responsible for exponentially more deaths than high body weight.
- There is something called the “obesity paradox” which has cardiologists confused; as Ernsberger says sarcastically, “These damn people just won’t die!” And I say, it’s only a paradox if you make the assumption that fat people are inherently worse off simply because of our weight.
- Studies of people with congestive heart failure show that fatter people do better
- Williams et. al, in 1997 (Eur Heart Journal) found no relationship between heart disease and body fat
A few other fun facts!
- Excess muscle tissue is what demands the heart work harder; 1 kg of “adipose tissue” (aka fat) uses only 19 kg/d of energy, where 1 kg of muscle tissue uses 55 kg/d of energy. Metabolic rate (how much energy one’s body uses) is therefore related to lean body tissue, not fat
- Studies of twins show that not just body weight but its distribution is identical; if one has a big butt, the other has a big butt. If one has big upper arms, the other will have big upper arms. If one has fat thighs, the other will have fat thighs. This is very strong evidence that body weight and its distribution are genetically determined.
- The only health problems which are proven by studies to be related to body weight are osteoarthritis in the knees, which is usually mechanical, and a higher incidence of uterine cancer in fat women due to higher estrogen levels.
- Fat people are at lower risk for many diseases (I’ll post the list when I get home).
- The experience and effects of someone deciding to diet once in middle age due to gaining a few pounds is completely different from the experience of people who diet all their lives (also known as “chronic restricted eating”)
OLD PARADIGM: Fat is due to lifestyle factors and diet only; fat is toxic; less fat means more health; disease in fat people is directly caused by fat.
NEW PARADIGM: Weight is regulated by setpoint, which results from a combination of genes, diet history, and lifestyle; body fat is something everybody has and everybody needs; disease is caused by weight cycling (yo-yo dieting) and genetics.