The ROS Theory of Obesity

At the beginning of this series I stated that any theory of obesity should be able to explain why a Chinese peasant eating a very low fat diet with the bulk of calories furnished by white rice – a refined carbohydrate – is lean, a French person eating a mixed fuel diet of starch, sugar, …

The Three Countries Study Read More »

Satiation is a feeling that is actually triggered in the brain by specific neurons in the hypothalamus. These neurons respond to a number of factors, including circulating levels of blood glucose, free fatty acids (ie energy availability) and hormones such as leptin. In this paper, the authors show that ROS is necessary for satiation. The …

ROS is Satiation Read More »

This paper measured the level of Stearoyl-CoA desaturase in morbidly obese adults compared to adults with a normal BMI. The obese adults produce 2-3 times as much of the enzyme as do lean adults, resulting in fat that is significantly more unsaturated. In addition, the obese adults also had much higher levels of polyunsaturated fats. …

The Body Fat of Obese Adults is Highly Unsaturated Read More »

A “knockout mouse” is a strain of mice in which a section of their DNA has been deleted. Therefore, they do not have a particular gene. Sometimes, this has disastrous consequences, certain genes they cannot live without and thus they are never born. But when a knockout mouse lives, it can teach us interesting lessons …

The Loss of SCD1 Prevents Obesity in Mice Read More »

When fat cells respond to insulin they take several actions in switching from fat burning mode to glucose burning and fat storing mode. These actions include: Turning off lipolysis – the process of releasing fats into the bloodstream as Free Fatty Acids which other cells can use energy Absorbing Glucose and beginning de no lipogenesis …

Butter Causes a High Level of Available Energy 8 Hours After a Meal Read More »

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 …

Long Chain Saturated Fat Causes Fat Loss in Mice Read More »

In this series we’ve discussed the fact that saturated fat oxidation leads to ROS production in the mitochondria which makes peripheral fat cells “physiologically insulin resistant” which prevents them from switching from fat burning to fat storage. We’ve shown that saturated fat reversibly induces insulin resistance in people in the short term and that a …

The Amount of Polyunsaturated fat in the Modern American Diet Fattens up Mice Without Additional Calories Read More »

In previous posts I have laid out the argument that metabolism of long chain saturated fat creates mitochondrial ROS which causes short term insulin resistance while the saturated fat is oxidized. Insulin tells the bodies cells to switch from fat metabolism to glucose metabolism and causes fat cells to absorb glucose, convert it to fat …

Saturated Fat Causes Physiological Insulin Resistance in Humans Read More »

In this series I often mention that mitochondrial ROS production creates physiological insulin resistance which keeps your cells in “fat burning mode”. In this paper, the authors actually took a picture of fat burning mode!! They asked human subjects to eat a low fat vegan diet for two days and then gave them a banana …

This Is What Fat Burning Looks Like Read More »

Let’s think about what happens in response to a starchy meal. Blood sugar rises and insulin is released. Insulin attaches to the insulin receptors on the cell membranes of muscle cells, fat cells, etc. The cells respond by moving a glucose transporter, GLUT4, into the cell membrane so that they can start importing glucose. Insulin …

Physiological Insulin Resistance Read More »

In the introductory series, we first saw an example of ROS (Reactive Oxygen Species) as a signal in a small worm (nematode) called c. elegans. When glucose oxidation in c. elegans is blocked, the worms shift to burning fat which creates more ROS which ultimately leads to a longer lifespan for the worm. Why does …

A Highly Conserved Molecular Bottleneck Read More »