A high carbohydrate diet shifts insulin signaling from muscles to fat stores
Wouldn’t it be great if the foods we eat, would mainly feed the muscle instead of being stored as fat? A study conducted by S. Devkota and D. Layman shows that if mice receive a diet high in protein, at the expense of carbohydrates, more glucose will be directed to the muscle and less will be stored as fat.
Sedentary mice were given either a high carbohydrate diet, where the energy came for 60% from carbohydrates, 12% from protein and 28% from fat. This nutrient composition is in agreement with the “general dietary recommendations” in most countries. The high protein group received the same amount of calories, but the energy came for 35% from carbohydrates, 35% from protein and 30% from fat. This diet reflected more a “Zone” type of diet.
This study showed significant differences in insulin signaling by simply decreasing the carbohydrate to protein ratio. They demonstrated that the high carbohydrate diet caused a shift in insulin signaling from skeletal muscle to fat stores. A high protein diet, at the expense of carbohydrates, made the muscles more sensitive for insulin, while it induced only slight signaling in fat tissue. In the high carbohydrate group, more glucose was stored as fat to cope with excess glucose provided by the diet. In addition, the high carb diet seemed to induce sings in the muscle that resemble insulin resistance. Apparently, the high carbohydrate diet makes the body skip the muscle as the main storage place for glucose and promotes glucose storage in fat tissue.
So, it appears that sedentary individuals that follow the “general recommendations” shift their insulin sensitivity from their muscles to their fat stores. Happily, there is a simple solution for this problem: “exercise”. By performing regular physical activity, muscle becomes more sensitive to insulin. This allows the body to tolerate more carbohydrates, which can be channeled to the muscle. Still, it seems that a diet high in protein has benefits by promoting insulin sensitivity in the muscle. It is clear from this study that nutrients are important signaling molecules and they should not be categorized solely as energy providers.
Excerpt image by fitness-healthandbeauty.com
Devkota, S., & Layman, D. K. (2011). Increased ratio of dietary carbohydrate to protein shifts the focus of metabolic signaling from skeletal muscle to adipose. Nutrition and Metabolism, 8