Are calories all the same, regardless of source? In a test tube, yes, all calories burn the same. However, human metabolism is vastly different.
Harvard researchers supported this point by putting overweight individuals on 3 different diets over a 7-month period, with each diet containing the *same amount of calories*.
Diet #1 – 60% carbs, 20% protein, 20% fat
Diet #2 – 40% carbs, 20% protein, 40% fat
Diet #3 – 10% carbs, 30% protein, 60% fat
Individuals on diet #3 had the greatest total energy expenditure (calories burned) per day. In fact, the high-fat diet (#3) allowed the individuals to burn 300 calories more per day vs the low-fat, high-carb diet. This is equivalent to running an hour per day without doing any exercise.
The high-fat diet also led to improved insulin resistance, cholesterol, triglycerides, lower LDL, and lower levels of PIA-1 (a marker for blood clots or inflammation).
Conclusion: focus on food quality, not calories. Different calories have different effects on cell biology. Constant high blood sugar + insulin = fat storage. Insulin can also block the signaling of leptin, your “I’m full” hormone.
It’s important to note that the carbohydrates described in this study were fast-digesting carbohydrates. Vegetables are slow-digesting carbohydrates that do not raise insulin, are low in calorie and enhance metabolism. The group eating 60% fat was in terms of calories, and fat is dense in calories. Therefore the bulk of your plate should consist mostly (~75%) of colorful vegetables. The remaining 25% should be healthy fat and protein. Once again, fat is dense in calories. So while it may only take up 15-25% of your plate, many of your calories will come from fat.
Many diets can *eventually* lead to weight-loss, but which one is most efficient and sustaining? Nutritional research is constantly evolving, but what’s important is eating real food in its natural form. There are no Pop-Tart trees.
Ebbeling, C. B., Swain, J. F., Feldman, H. A., Wong, W. W., Hachey, D. L., Garcia-Lago, E., & Ludwig, D. S. (2012). Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance. Jama, 307(24). doi:10.1001/jama.2012.6607