Pros and cons to the keto diet

In recent years, the keto diet, or ketogenic diet, gained popularity among dieters looking to shed extra pounds. Kinesiology expert Dr. Richard Kreider said these low-carbohydrate, high-fat diets can be beneficial for some people trying to lose weight, but may not be helpful for active individuals or athletes.

Kreider, a professor in the Department of Health and Kinesiology, has been conducting weight loss research for 30 years. Previously, he focused on comparing popular weight loss programs like Curves and Weight Watchers. As a kinesiology researcher, he also aims to find solutions for competitive athletes.

His recent study explored how ketogenic diets affect strength-trained women. Kreider said in comparison to the available literature on men, there was a lack of research on how ketogenic diets affect trained women.

How keto works

A normal, heart-healthy diet is comprised of about 55% carbohydrates, 30% fat and about 15% protein. No foods are off-limits, but moderation is encouraged. A ketogenic diet generally allows for less than 50 grams of carbohydrates per day, or about 200 calories, 60% to 80% fat and about 10% to 15% protein. Meats, vegetables and dairy are encouraged, but sugar is a no-go.

“The advantages of high-fat diets are they help you stay full and feel full, so you are not as hungry,” Kreider said.

When paired with resistance training, a form of physical activity that strengthens muscles, the keto diet can help the body turn fat into fuel, causing a reduction in fat mass. However, the diet may make it more difficult to train harder and build muscle.

“As you get used to different diets, the expression of your genes that burn carbohydrates and fats can change,” Kreider said. “So, if someone follows a high-fat diet, their fat metabolism genes can increase their expression, and therefore, burn more fat as a fuel during the day.”

However, Kreider said due to restricted carbohydrate intake, carbohydrate-related gene expression also declines and active individuals may not have as much energy to accomplish daily activities.

Applications for athletes

Kreider and his research team found that ketogenic diets can help decrease fat mass in strength-trained women, which can be helpful for female figure athletes, or athletes that needs to cut fat. However, he also warned that ketogenic diets may not be good for athletes.

“All athletes need enough carbs to meet their energy needs,” Kreider said. “While ketogenic diets may help promote fat metabolism and reduce body fat, they may also make it more difficult to train heavily and slow the ability to build muscle. Thus, adherence to a ketogenic diet may be counterproductive for athletes needing to maintain or build muscle.”

Figure athletes with aesthetic aspects to performance, for example, dancers, skaters, divers or female bodybuilders, who need a lot of muscle mass to perform well, but also need to keep body fat low may benefit. Whereas, long distance runners or ultra-endurance event competitors would not benefit because they need more carbohydrates to go the distance.

Applications for the everyday individual

Kreider said adults trying to lose weight who are pre-diabetic or diabetic may benefit from a lower carbohydrate ketogenic or higher-protein, low-fat diet, particularly when paired with resistance training. A ketogenic or higher-protein, low-fat diet are lower in carbohydrates, which is key for individuals managing their glucose.

“When you lose muscle, you lose glucose metabolism as well,” Kreider said. “When you gain muscle, your insulin sensitivity goes up, helping manage glucose levels, which can be particularly helpful in pre-diabetic and diabetics.”

However, Kreider warns that if you follow a high fat ketogenic diet and do not lose weight, the excess dietary fat may make it more difficult to maintain healthy cholesterol and blood lipid levels.

“As long as there is weight loss, there seems to be beneficial changes to blood lipids,” Kreider said. “But if you are not losing weight on these diets, then you have a really high dietary fat content, a lot of triglycerides in your diet, and your cholesterol levels may actually go up, even with training.”

Kreider recommends a lower fat and higher protein diet with exercise as a way to promote healthy weight loss, but warns against focusing too much on cardiovascular training without resistance training. He said he often sees women spending too much time on the treadmill attempting to get in the “fat-burning zone”.

“The take home message for those trying to manage weight is that you have to incorporate resistance training, because if you lose weight without resistance training, you typically are losing muscle too — and the muscle is the engine that burns the calories,” Kreider said.

Future research of Kreider’s will focus on higher protein and moderate carbs and low-fat diets, as well as diet cycling and intermittent fasting-type diets.

“A lot of people will lose weight and then hit a plateau,” Kreider said. “We are trying to find ways to help people prevent that through exercise and diet manipulation.”