In a landmark paper published in Cell Metabolism in September of 2018, John Speakman, (with joint appointments at University of Aberdeen and the Chinese Academy of Sciences) et al., studied the effects of 29 different diets that varied in protein, fat and sucrose content on food intake, adiposity and energy expenditure in 5 strains of mice. These diets are meant to model the American diet in terms of their fatty acid composition and carbohydrate composition.
The impetus for the study lies in the still not well understood relationship between dietary macronutrient composition and subsequent food intake and body weight gain. Put more simply, is obesity driven by excess energy intake when the diet is high in one macronutrient (fat, protein, carbohydrate)?
Speakman’s data from over 1000 mice showed that in these models, it was dietary fat that was the most responsible for increased adiposity. As the amount of fat in the diet increased (in the face of high or low dietary protein), the mice consistently gained more weight. Altering dietary protein or sucrose levels did not have a significant effect on weight gain. As stated in their discussion, “When dietary fat levels are fixed, variation in other macronutrients appears largely irrelevant for weight and adiposity regulation.”
Researchers wanting to test these macronutrient combination diets in their own animal models can see the formulas below. They can be ordered as they appear or we can modify these diets to create new formulas to answer related research questions.
Dr. Speakman’s entire diet series can be found here:
- Series One: 20 kcal% fat content with variable protein from 5 to 30 kcal% and carbohydrate changing from 75 to 50 kcal%. Sucrose is fixed at 5 kcal%.
- Series Two: 60 kcal% fat content with variable protein from 5 to 30 kcal% and carbohydrate changing from 35 to 10 kcal%. Sucrose is fixed at 5 kcal%.
- Series Three: Protein at 10 kcal% with variable fat from 10 to 80 kcal% and carbohydrate changing from 80 to 10 kcal%. Sucrose is fixed at 5 kcal%.
- Series Four: Protein at 25 kcal% with variable fat from 8.3 to 66.6 kcal% and carbohydrate changing from 66.6% to 8.3 kcal%. Sucrose is fixed at 5 kcal%.
- Series Five: Protein at 25 kcal%, fat at 41.7 kcal% and carbohydrate at 33.3 kcal%. Sucrose varies between 10 and 30 kcal% (5 levels).
Dr. Speakman was recently interviewed about this paper: https://soundcloud.com/radiosputnik/this-is-probably-the-biggest-study-thats-been-done-in-nutrition-in-50-years-lead-scientist