Low Carb Diet to Preserve Muscle Mass?
When it comes to diet there is not a cookie cutter approach that works for everyone. We are all individuals and should be viewed that way. This becomes really clear when you prepare someone for a bodybuilding or figure show. You might see some clients who need a drastic reduction in carbs (maybe even 0 carbs), someone who doesn’t need as much cardio as the next guy or that asshole that can eat Mcdonald’s and stay lean.
In a recent study from BioMed Central a group of researchers found that preservation of muscle mass IS possible with a “very-low-carbohydrate” diet.
Let’s examine their findings
We have been led to believe that a low carb diet inevitably leads to catabolism and significant muscle loss. The reasoning behind this was that the body would recruit amino acids from muscle proteins to help maintain blood glucose levels during gluconeogenesis. Some physiologists will argue that free fatty acids cannot be utilized in gluconeogensis but recently there has been research showing that there may be pathways where this IS possible. Normally, the body will primarily use amino acids and the glycerol backbone from triglycerides to fuel gluconeogeneis. However, the authors note that during a very low carb diet, mobilization of fatty acids is accelerated thus leaving the liver to produce ketone bodies. The liver isn’t able to effectively use the ketone bodies so they then disperse to extra-hepatic tissues where they are then used as fuel. For example, during this carb restriction the brain will be fueled by stored fat. The remaining glycolitic tissues that require glucose also derive their energy indirectly from fat stores.
Also, during the low carb diet insulin levels are decreased along with an increase in glucagon. Insulin has a host of properties including glucose and amino acid uptake and stimulating anabolic processes (fat synthesis, protein etc). Glucagon will be releasing glucose, increasing gluconegenesis and fat mobilization. When insulin is low our body is not able to use glucose as fuel thus increasing our reliance on stored fuel. This is part of the reason why low carb diets or carb cycling are effective in fat loss.
What the studies showed
- A group of men were fed a 1,000 kcal very low carb diet (10g a day) for 10 days. After the 10 days of the weight lost, 97% was fat.
- Another study by Young et al. compared 3 diets of 1,800kcal, 115g of protein, and 3 different carbohydrate amounts (30g, 60g, 104g). After 9 weeks the group with 30g of carbs lost the most fat, 60g group was second and 104g came in last. Of the weight lost the 30g group was 95% fat, 60g group 84% fat, and 104g group 75% fat.
- A study by Volek et al. looked at the results of a 6 week low carb diet in healthy normal weight men. The men went from eating a diet with 48% carbs to 8% (there was also a control group). By week 6 the results showed a -3.4kg (roughly 7.5lbs) loss in fat mass and a +1.1kg increase in lean body mass.
- A few other studies were presented as well that echoed these results.
How the researchers explain this
- Low blood sugar will secrete adrenaline and “skeletal muscle protein mass is also regulated by adrenergic influences”
- As noted above, ketone bodies help spare muscle tissue by allowing muscle to be supplied with fatty acids and ketones thus limiting oxidation of muscle protein amino acids.
- Low blood glucose levels will increase Growth Hormone secretions. Growth hormone is an anabolic hormone and has a host of muscle building and fat burning properties.
- Normally during a low carb diet the dieter will include a lot of protein. Studies show that high protein intake increases protein synthesis. For any of us that have dieted or experimented with low carb or carb cycling, you usually increase protein as carbs go down.
What to make of this data
Now before you cut out all of your carbs ask yourself, is my diet working? If the answer is yes, then don’t mess with it! Would I recommend a very low carb diet? Depends on the person AND goals, usually I don’t though. But this data is interesting and can still be useful. I have found that carbohydrates help keep people sane during dieting and as I wrote before, the best diet is the one that is SUSTAINABLE. Some people feel awful on low carbs and so they probably won’t be able to follow the diet as they have become pretty inefficient at using fat for fuel. Carbs also increase serotonin which has a calming effect on the body. This is why all you fat bastards are tired all day long after you stuff your face with carbohydrates at every single meal.
Ok, so then why is this useful? Well, it is another reminder that typical bro-science isn’t always right. Low carb doesn’t necessarily need to result in muscle loss nor do we need to eat every 2-3 hours to “maintain our metabolism”. If you can eat a ton of carbs and lose weight, then I’m happy for you. For most, they will require some drop in carbohydrates and this is a promising study for those of us hoping to maintain lean mass during low carb. In my upcoming article for Elitefts I discuss how I set up fat loss days/muscle gain days by understanding the relationship between AMPK and mTOR and their effects. This research further supports that the body isn’t some inefficient, muscle burning machine; instead our body is pretty smart AND efficient. Since I am a firm believer in fasting as a tool in dieting this is an alternative for those of you terrified of fasting. Don’t be afraid to go carbless for extended periods of time, there are a host of benefits (insulin sensitivity for example), oh and some fat loss too. Stay Hungry.
Manninen*, Anssi H. “Very-low-carbohydrate Diets and Preservation of Muscle Mass.” Nutrition & Metabolism. BioMed Central, 31 Jan. 2006. Web. 28 Sept. 2012.