Most people make a big deal about protein. I do, too. Low carb diets aren’t muscle-sparing. Again.
Comparison of a Low-Fat Diet to a Low-Carbohydrate Diet on Weight Loss, Body Composition, and Risk Factors for Diabetes and Cardiovascular Disease in Free-Living, Overweight Men and Women (Meckling et al., 2004)
Part 1. Hunger Free Diet(s)
Focus on what they’re eliminating:
LC diet: “limit intake of breads, pastas, rice, and desserts, eliminating intake of deep-fried foods, dried fruit, candy, sweetened soft drinks, and sugar, and increased consumption of vegetables, lean meats, eggs, and nuts”
LF diet: “eliminate high-fat dairy products and substitute with no-fat or LF alternatives, to increase intake of fruits, vegetables, whole-grain breads, and pastas and to eliminate fried foods, cream sauces, and high-fat/sugar cakes, pastries, chocolate, and candy. They were also asked to reduce use of oil products in cooking. As with LC subjects, LF subjects were encouraged to consume lean meats as alternatives to high-fat meat products.”
I don’t care much for “LF alternatives” like low fat yogurt or skim milk, but for the purpose of this study (LF/CICO), it gets the job done. Both of these are healthy, Hunger-Free Diet(s). And neither are extreme.
Part 2. Dismay!
LC dieters lost less fat and more muscle than LF dieters.
So I immediately thought it was either CICO or protein. The LC group must not have cut enough calories (to explain the “less fat loss”) and cut too much protein (to explain the “more muscle loss”).
Maybe insulin didn’t decline in LC for some odd reason?!!!
Part 3. Chill, guys.
3a. regular conclusion: Both groups started eating better, lost fat mass, and got healthier.
3b. alternative conclusion: Low carb diets aren’t muscle-sparing and even appear to be the opposite: you need to increase protein to attenuate muscle loss on this diet. These LC dieters increased protein by 10 g/d and still lost more muscle than LF dieters, whose protein actually declined by ~10g. If LC was muscle-sparing, the exact opposite would’ve happened. It didn’t. Please don’t hate me for this.
Keto works very well for many people! I’d just say it’d be prudent to increase protein and maybe even take up resistance exercise to spare/preserve lean mass.
Further reading: Muscle growth sans carbs