I wrote the other day about the less-than-optimal control animals and humans used in fasting and calorie-restriction studies. Partly this is due to the bad food that most people eat, as well as the substandard lab food that rats and mice eat. A similar problem exists in other diet experiments on lab animals. Here I’ll show that a high-fat diet doesn’t cause obesity – in lab animals anyway.
If you read much of the scientific literature, you’ll come across lots of studies using lab rats and mice that were fed “high-fat” diets. Usually they produce ghastly results, like obesity, diabetes, cancer, cognitive deficits, and so on. Then the mainstream media trumpets these as meaning that you are going to get sick and die if you eat a high-fat diet.
Just to pull one more or less at random, “High-Fat Diet Disrupts Behavioral and Molecular Circadian Rhythms in Mice“. Control mice ate the Harlan Teklad 7012 diet of standard lab chow. It’s 25% protein, 17% fat, and 58% carbohydrate. Importantly, it contains no sugar and has high-quality, natural ingredients.
The high-fat group ate Research Diet 12451. Here are the ingredients:
This diet is 35% carbohydrate, 20% protein, and 45% fat. It contains sucrose – table sugar – as 17% of calories, as well as soybean oil, maltodextrin, and casein.
That amount of sugar is comparable to what the typical obese and heart-disease-prone American eats. Soybean oil has a high omega-6 content. Maltodextrin is a simple carbohydrate that turns to maltose and then glucose when absorbed, spiking blood sugar and insulin. Casein supplies all the protein, whereas the standard lab chow has no animal protein.
Yes, of course animals eating this garbage get sick.
In contrast, look at another paper: A high-fat, ketogenic diet induces a unique metabolic state in mice. The animals on the ketogenic diet had lower body weight, lower glucose and insulin, and higher AMPK activity, a pro-longevity mechanism. When animals were switched to this diet, they lost weight. All very healthy, yet it was a high-fat diet, with 95% fat, 5% protein, and 0% carbohydrate. A very high-fat diet.
One of the experimental arms in this experiment was on the Research Diet 12451, as illustrated above. They got fat and sick.
The animals on the “high-fat” diet in the first study were in reality eating a high-sugar, moderate-fat diet. Very misleading, if you ask me.
The animals in the second study ate a very high fat, no carb and sugar diet, and were healthy.
So next time you read about a high-fat diet making animals sick, diabetic, obese, or whatever, you can’t take it at face value.