If you’ve been reading along you know that by this point we’ve shown that long chain saturated fat consumption causes ROS production in the mitochondria which causes short term physiological insulin resistance. The ROS theory of obesity suggests that physiological insulin resistance should prevent fat storage in peripheral fat cells (adipocytes).
I’ve been dancing around the topic but I’ll put it on the record now. Unsaturated fats (or short chain saturated fats) do not generate as much ROS in the mitochondria and tend to promote insulin sensitivity. Insulin sensitivity should lead to fat gain. Let’s see what happens in wild type (regular) mice.
Valerie Reeves thesis compared wild type mice fed either a typical “chow” diet (17% of calories from fat), a “Stearic Acid” diet (40% of calories from fat, 85% of it as stearic acid, a long chain saturated fat), or an “oleic acid” diet (40% of calories as fat, roughly two thirds as mono-unsaturated fat and one third as polyunsaturated fat). The feeding happened for 10 weeks with the mice having free access to as much food as they wanted. The results are as shown.
Let’s look at the top graph first. The first bar is the weight of the mice before the ten week experimental diet. The second bar shows that the low fat (chow) fed group increased in weight from around 21g to 28g over the ten weeks. The third bar is the mice fed the diet high in long chain saturated fat (stearic acid). That group may have lost a gram of weight over the ten weeks! The final bar is the mice fed 40% of calories as unsaturated fat. They gained about as much as the low fat control diet.
The lower graph shows only the fat mass of the mice. As you can see, the low fat chow diet mice maintained their fat mass over the ten weeks, the long chain saturated fat stearic acid (long chain saturated fat found in beef and chocolate) mice lost close to half of their body fat and the mice fed oleic acid (long chain monounsaturated fat found in olive oil and avocados) had a significant gain in body fat.
A Second Study
In this study , the authors used a strain of nude mice and found the same result. The mice were all given lower fat diets compared to the previous study, around 20% of calories as fat. The diets were described as “a low fat diet (5% corn oil diet) comparable to normal rodent chow, a 20% safflower oil diet, a 17% corn oil/3% safflower oil diet and a 17% stearic acid/3% safflower oil diet.”
The mice fed a diet supplemented with stearic acid, as opposed to a low fat diet or a diet supplemented with corn oil or safflower oil, consumed the most calories, had the lowest body fat and the highest total lean body mass.