Keto Diet Keeps Aging Mice Strong Without Building Muscle

Highlights:

• Aged mice fed ketogenic diets show improved muscle strength and coordination compared to mice fed normal diets.
• These improvements in muscle performance were not linked to increases in muscle size but, instead, to increases in the connectivity between the nervous system and muscles.

​​The ketogenic diet is all the rage as a fat-loss method, but will it really help you stay strong (or even get stronger) as you get older.

According to new pre-publication research, ketogenic diets increase strength and muscle function in elderly mice, but not by making muscles bigger. So, how can a diet make an animal stronger and have better coordination and balance without growing bigger muscles.

Scientists from three different universities—the University of Missouri, Ohio State, and Wisconsin—discovered that a ketogenic diet appears to influence the connectivity of the nervous system to muscles. Their work demonstrates that aged mice given ketogenic diets had a higher density of neurons supplying their muscles, which translated to improved strength and functionality (i.e, balance and coordination).

This study’s findings, which are now being reviewed at The Journal of Nutrition, Health, and Aging, corroborate those of earlier studies that found that ketogenic diets may help older adults improve or maintain their motor function, even as they age.

How Muscle, Getting Older, and The Nervous System are Connected

Our movement, whether performing everyday tasks or trying to get in a workout, gets limited as we age. The older we get, the more we tend to lose muscle mass and, ultimately, endurance and strength. Part of the reason this happens is because cells have less energy to work with due to a reduction in the number and function of mitochondria, the power engines of the cells. 

Some people think that the best way to combat weakening muscles with age is to increase muscle size—the bigger the muscle, the stronger the muscle.

But there is building evidence that deteriorating muscle strength actually has quite a bit to do with the nervous system that controls how the muscles work. In other words, if the nerves controlling the muscles are weak, the muscles themselves will be weak too.

Even with this knowledge, few interventions have been investigated for improving muscle wasting through targeting the nervous system.

Ketogenic Diets Help Nerves that Control Muscles During Aging

For almost a century, the ketogenic diet has been used in the treatment of drug-resistant epilepsy. Recent studies suggest a wider, neuroprotective role of the ketogenic diet in the context of cancer, neurodegenerative diseases, and normal, healthy aging.

The purpose of this study was to examine the impact of a ketogenic diet on the skeletal muscles (as opposed to the “cardiac” muscles found in the heart) of older mice. They accomplished this by subjecting older mice to a ketogenic diet for 10 weeks or a “normal” diet, and then testing their muscle strength and functionality using a battery of tests.

Researchers measured the animals’ muscle strength—the amount of force a group of muscles can pull—by testing their grip strength. To test muscle function—how well the mice could coordinate and balance their movements—the researchers used the Rotarod test, which is similar to trying to stay balanced on a log in water. The Rotarod test is one of the most common ways to look at motor impairment in mouse models of neurodegeneration because it is very sensitive to changes in muscle function. 

For both types of tests, the ketogenic diet performed better; they were able to pull more force with their limbs and maintain their balance on the rotarod for longer periods of time.

To see what was underlying these improvements in muscle strength and functionality, the researchers first looked at whether there was an effect on muscle size because increased strength is often coordinated with bigger muscles. However, they didn’t see any differences in the muscle sizes between aged mice fed “normal” or ketogenic diets.

What they did find was that these improvements in muscle strength and functionality were linked to certain improvements that relate to the nervous system that controls the muscles. Specifically, they saw that aged mice fed ketogenic diets had increased numbers of functioning motor units—the approximate number of motor neurons that connect to a single muscle or a small group of muscles.

To sum up, these results show that a ketogenic diet can enhance motor function in old mice, and this enhancement may be associated with better muscle-motor unit connectivity. The results presented here lend credence to the idea that ketogenic diets may help older people with motor function issues, and they also lend credence to the idea that such diets may help younger people with similar issues.

How does a ketogenic diet work?

The ketogenic diet aims to force your body to use a different type of fuel. Instead of relying on sugar (glucose) that comes from carbohydrates (such as grains, legumes, vegetables, and fruits), the keto diet relies on ketone bodies, a type of fuel that the liver produces from stored fat. This process is referred to as ketosis .

Fat burning sounds like the perfect weight-loss strategy. However, motivating the liver to produce ketone bodies is not an easy task:

• You need to cut out carbs—less than 20 to 50 grams daily (a medium banana has about 27 grams of carbs)—in order to do this.
• Getting into ketosis usually takes a few days.
• Overconsumption of protein might throw off your ketosis progress. 

What does a ketogenic diet look like?

Many versions of ketogenic diets exist, but all ban carb-rich foods. Some of these foods may be obvious: starches from both refined and whole grains like bread, cereals, pasta, rice, and cookies; potatoes, corn, and other starchy vegetables; and fruit juices. Some that may not be so obvious are beans, legumes, and most fruits.

Most ketogenic plans allow foods high in saturated fat, such as fatty cuts of meat, processed meats, lard, and butter, as well as sources of unsaturated fats, such as nuts, seeds, avocados, plant oils, and oily fish. Depending on your source of information, ketogenic food lists may vary and even conflict.

Almost all ketogenic diets tend to share the following ingredients:

• Moderate amounts of protein (such as fish, chicken, turkey, lean pork and beef, eggs, and cheese)
• Small amounts of low-carb vegetables (such as broccoli, spinach, asparagus, cauliflower, and kale)
• High amounts of fat (nuts, seeds, avocado, olive oil, and olives).

Whether the health benefits of ketogenic diets extend to higher-risk individuals with multiple health conditions and the elderly is the main question that has not been answered. For the time being, it is not known whether a ketogenic diet can treat or prevent any age-related illness.

You should not, however, go into your journey to a longer and healthier life expecting a miracle from a ketogenic diet.