“I want to try building muscle on a ketogenic diet,” a reader told me the other day.
“I’ve seen a study showing that it’s the best way to lose fat and gain muscle. What do you think about it?”
It would be great if there was one single diet that worked best for muscle growth, fat loss, athletic performance, optimal health or whatever else you can think of.
Unfortunately no such diet exists.
If your goal is to gain the maximum amount of muscle in the shortest amount of time, the diet you follow will be very different to one designed for fat loss.
I’ll explain why in a moment.
First, I want to address a few of the issues with the study supposedly showing that a ketogenic diet is the “best diet” to build muscle and lose fat.
Publishing their findings in the journal Metabolism, a group of researchers from the University of Connecticut tracked changes in body composition in a group of healthy, normal-weight men.
Of the 20 men taking part in the study, 12 switched from their normal diet to a low-carbohydrate ketogenic diet for six weeks. The other eight men continued with their normal diets.
Foods eaten on the low-carbohydrate diet included beef (steak and hamburgers), cheese, eggs, peanut butter, various nuts and seeds, vegetables and protein powder (Super Whey Fuel and Fuel Plex Lite).
Subjects were also told to avoid fruits and fruit juices, dairy products (with the exception of hard cheese and heavy cream), breads, cereals, rice, beans, and sweets.
The men kept a food diary each day of the study (seven days during baseline and 42 days during the low-carbohydrate diet) and the control group kept seven-day records during weeks one and six.
Here’s what daily nutrient intake looked like in both groups during the final week of the study.
Total calories 1,949 calories
Protein 80 grams (16% of total calories)
Carbohydrate 283 grams (58% of total calories)
Fat 56 grams (26% of total calories)
Ketogenic diet group
Total calories 2,334 calories
Protein 176 grams (30% of total calories)
Carbohydrate 46 grams (8% of total calories)
Fat 157 grams (62% of total calories)
And the result?
Total fat loss at the end of the six-week study was just over seven pounds in the low-carbohydrate group. The group following their normal diet lost no weight.
The men on the low-carbohydrate diet gained just over two pounds of muscle. The control group, on the other hand, gained just under one pound.
However, while the low-carbohydrate group gained twice as much muscle as the control group, this doesn’t necessarily mean that such a diet is the best way to pack on size.
The first problem is that there was a big difference in protein intake between the two groups.
A closer look at the food records reveals that subjects on the ketogenic diet ate TWICE as much protein than those in the control group (176 grams versus 80 grams per day).
The extra muscle growth in the low-carbohydrate group was most likely down to the fact they were eating more protein.
What’s more, the low-carbohydrate diet was designed to promote weight loss, rather than weight gain. Muscle growth is usually a lot faster with a diet providing more calories and more carbohydrate than both of the diets tested in this trial.
Taking six weeks to gain two pounds of muscle is nothing to write home about, especially when you compare it to the 5-6 pound muscular gain seen with higher carbohydrate intakes over the same period (such as here and here).
This brings me to the subject of exercise.
In an ideal world, both groups would have followed the same exercise program. But that doesn’t appear to have happened in this study. The only information about the type of training routine used in the research was this…
Subjects were moderately active performing a variety of different aerobic and weight-training routines, but none were competitive athletes. In the carbohydrate-restricted diet group, 1 subject was sedentary, 5 performed regular exercise (2 to 4 times per week for 20 to 60 minutes) and 6 performed a combination of aerobic exercise (3 to 5 times per week for 15 to 90 minutes) and resistance exercise (2 to 6 times per week for 45 to 120 minutes). Subjects were required to maintain their current level of physical activity during the study.
What this means is that all of the subjects in the low-carbohydrate group were following a DIFFERENT exercise program, and we have no idea what sort of exercise the control group was doing.
In other words, any differences in muscle growth between the two groups could have been due to a better training program rather than diet alone.
Even the lead author of the study, Dr Jeff Volek, believes that more carbohydrate is needed if you’re trying to build muscle.
Volek, a former Indiana state champion in powerlifting, is the co-author of numerous articles in scientific journals, with a number of book chapters, research presentations and abstracts wedged under his lifting belt.
“If you are trying to gain weight, my experience is that it is very difficult to prevent weight loss, let alone gain weight, on a strict ketogenic diet,” says Volek. “When you start doing higher repetitions like bodybuilders do, at least during some phases of their training, I do think there’s probably going to be some compromise in your ability to do those sets.”
In short, ketogenic diets are not ideal as far as muscle growth is concerned. They work just fine if you want to lose fat, although they offer no advantage compared to non-ketogenic low-carbohydrate diets where you get 30-40% of your total calories from carbs.
If you enjoyed this post, there’s a good chance you’ll also like Truth and Lies about Burning Fat: 10 Weight Loss Myths Debunked By Science.
It's a FREE 16-page special report (PDF) I put together to debunk 10 popular weight loss myths that are still widely believed, despite all the evidence to the contrary. You can download a copy here.
About Christian FinnChristian Finn holds a master's degree with distinction in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Fit Pro, Zest, and Perfect Body magazine.