Ketogenic diets have become very popular over the past couple of years. In case you've been living under a rock, a keto diet is a high fat, moderate protein, very low carb diet. Do keto diets improve weight loss? Yes, they do. Now, here comes what seems to be my new catch phrase: "There's a difference between weight loss and fat loss."
Carbs And Water In The Muscle
Glycogen is a form of glucose (carb) that is stored in muscle and the liver. Along with every gram of glycogen stored, there are also 3-4 grams of water stored with it inside the muscle. There was a study that looked at ketogenic dieting and after four days, the participants lost an average of 9.48 pounds; however, the catch is that 3.66 of those pounds came from glycogen and water. That means approximately 40% of the weight lost didn't even come from fat! [1]
Muscle
Another flaw you will see in many of the studies praising keto diets is that they do not match the protein intakes between the keto and non-keto groups. Why does this matter? It matters because, when dieting, you will experience lean body mass loss if your plan isn't structured properly, and muscle contributes to the weight lost in these studies. While on the topic of muscle, I will throw in a quick note. While keto diets do show some promise for ultra endurance athletes (aka people running 50k or further), they are not great for resistance training.
Fat Loss
Now, here's the part you came for. Do keto diets improve fat loss? No they do not. Studies show that when the Calories consumed are equal between groups, the way the Calories are distributed between carbs and fats, makes very little difference. A couple of studies even showed greater fat loss and reduction in waist circumference in the higher carb group vs. the keto group. [2][3]
Takeaway
Before you who are in favor of keto diets start throwing stones at me, I am not saying keto diets don't work. You can certainly lose fat on a keto diet. I know several people who have. What I am saying, is that they are not better than a moderate carb diet. If you prefer to eat higher fat, do that. If you prefer to eat higher carb, do that. Just make sure you are fitting what you eat in your Calorie needs for the day.
Thank you guys for reading (or I suppose listening if you're taking advantage of the new audio version of the blog). I will be back next week with another fat loss topic for you. As always, God bless you AND your family and I'll see you next week.
References:
[1] Kreitzman, S. N., Coxon, A. Y., Szaz, K. F. (1992) Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition, The American Journal of Clinical Nutrition, 56(1), 292S-293S
[2] Johnston, C. S., Tjonn, S. L., Swan, P. D., ... Sears, B. (2006) Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets, The American Journal of Clinical Nutrition, 83(5), 1055-1061
[3] Sacks, F. M., Bray, G. D., Carey, V. J., ... Williamson, D. A., (2009) Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates, The New England Journal of Medicine, 360, 859873 DOI: 10.1056/NEJMoa0804748
