A mind-boggling variety of dietary approaches exist for losing weight. May so-called diets are neither healthy nor sustainable. You may have heard people speak of ketogenic diets as a way to lose weight. What is a ketogenic diet and what type of benefits does such a diet offer?
What is a Ketogenic Diet?
Ketogenic diets have an interesting history. This type of diet has been used successfully for decades to help children with seizures gain control over their seizure symptoms. No one is exactly sure how ketogenic diets reduce the frequency of seizures but they work. Some children treated with such a diet are able to get off seizure medications. These days, ketogenic diets are also used as a weight loss diet with moderate degrees of success.
A ketogenic diet is very low in carbohydrates. People who follow this diet must keep their total daily carb count under 50 grams per day, although most ketogenic diets restrict carbohydrates to 20 grams daily. As a result, most of their daily calorie intake comes from protein and fat. The goal, with this diet is to deplete muscle and liver stores of glycogen. When glycogen is depleted, hormonal changes take place – insulin levels decrease and glucagon, a hormone that promotes fat breakdown rises. In response, your body taps into stored fat as a major fuel source since glycogen isn’t available.
Certain tissues in your body can’t use fat as a source of fuel, including your brain and retina inside your eyes. These tissues depend on glucose. As an alternative, they can use ketone bodies formed from the breakdown of stored fat. As fat breakdown increases, cells begin to make ketone bones. These ketones supply glucose-deprived tissues like the brain with the energy they need.
Weight loss is rapid when you first begin a ketogenic diet. Most of the weight lost during the first week is water – not fat. As glycogen stores are depleted due to the minimal quantities of carbs you’re consuming, water is lost along with the glycogen since the two are bound together. As you might expect, fat loss occurs on a ketogenic diet since this diet forces your body to break down stored fat as a fuel source. Insulin sensitivity also improves on a ketogenic diet.
Are There Drawbacks to a Ketogenic Diet?
A ketogenic diet sounds good in theory if you’re trying to lose weight. This very low-carb diet forces your body to break down stored fat by depleting it of glycogen – but there are drawbacks to such an extreme diet. For one, it’s very hard to maintain. Classic ketogenic diets are based on a ratio of fat to protein/carbs of 4 to 1. This means you’ll take in 4 grams of fat for each gram of protein and carbohydrate you eat. Not an easy ratio to maintain, even if you love fatty foods. Most people feel bad the first few weeks on a ketogenic diet. They feel tired and may have “brain fog.” Plus, having a high level of ketones gives your breath and urine a fruity smell. Not very good for your social life!
High-intensity exercise is more difficult in a carb and glycogen-depleted state. Your muscles need glycogen stores to work out at a high intensity since glycogen is their preferred fuel source during vigorous exercise. Being carb-depleted can also make it more difficult to build lean body mass. When you have low glycogen stores, not only does your body tap into fat as a fuel source during exercise, it breaks down muscle to convert the amino acids to glucose in an attempt to gain more glucose.
Interestingly, some bodybuilders adopt this diet, believing it will help them shed body fat. The problem is a ketogenic diet would theoretically make it harder for them to build muscle. In reality, most bodybuilders don’t follow a true ketogenic diet. The typical bodybuilder eats such large amounts of protein that it negates the effects of the ketogenic diet. For a ketogenic diet to be effective, your insulin level has to stay low. Even a small rise in insulin reverses the benefits of this diet by blocking fat breakdown. When bodybuilders consume lots of protein, insulin goes up. Protein, like carbohydrates, increases insulin production, although to a lesser degree.
In addition, when bodybuilders eat a lot of protein on a ketogenic diet, a portion of those amino acids are converted to glucose by the liver by a process called gluconeogenesis. Glucose from gluconeogenesis enters the bloodstream and is used as fuel by tissues. This influx of glucose is enough to counter the effects of a ketogenic diet. Even one large protein meal can do this.
Most people assume they can eat as much protein as they want on a ketogenic diet but doing so negates some of the fat loss benefits. The reason this diet is so high in fat is that fat doesn’t promote insulin release. The key to success with ketogenic or very low-carb diets is to minimize the amount of insulin circulating in your bloodstream so you can maximally break down fat. Diets very high in protein don’t do this.
Extreme Diets Rarely Work Long Term
Ketogenic diets have benefits for people who have seizures that are unresponsive to other treatments. Even these people have difficulty following this diet due to its very high fat content. If you’re trying to build lean body mass, you need protein – but with a ketogenic diet consuming too much protein will make the diet less effective. On the other hand, if you follow a ketogenic diet and limit protein, you may have problems building lean body mass.
A ketogenic diet has other drawbacks. Because you’re limiting carbs, you won’t be able to enjoy many fruits and vegetables. Children who are on a ketogenic diet for seizures usually have to take a multivitamin supplement to meet their nutritional needs. It’s not a balanced diet or one that works well if you’re trying to build muscle or do any form of high-intensity exercise. The best approach is to avoid “extreme” diets that severely restrict a particular macronutrient like carbs. Stick with the basics. Eat a clean diet with a healthy balance of macronutrients and combine it with regular physical activity – then you’ll see results.
References:
FitnessRX for Men. “The True Low-Carb Ketogenic Diet: What Went Wrong?” May 2014.
WebMD. “Ketogenic Diet for Epilepsy”
European Journal of Clinical Nutrition (2013) 67, 789-796; doi:10.1038/ejcn.2013.116; published online 26 June 2013.
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