Over the past few months we’ve received a number of inquiries regarding Dr. Sears’ stance on the Ketogenic Diet and how it relates to the Zone in terms of health and weight loss. Is this just the next diet craze or is it as good for weight loss and health as it’s touted to be?
What Is the Ketogenic Diet?
The ketogenic diet is a high-fat, low carbohydrate diet consisting of approximately 75% fat, 20% protein and 5% carbohydrate. Compare this to the Zone which is moderate in these macronutrients and supplies 30% fat, 30% protein and 40% carbohydrate as total dietary calories.
The Ketogenic Diet is based on getting the body into a state of ketosis (hence “keto”). Ketosis is a back-up metabolic system used to provide the brain with an energy source, called ketones, if glucose isn’t available or if blood levels fall too low.
What’s the Buzz About?
The popularity in the Ketogenic Diet stems from the quick weight loss it produces and its perceived health benefits. The diet is thought to increase the body’s ability to burn stored body fat and lower insulin levels. It’s important to note that the weight loss that stems from this diet isn’t necessarily fat loss, despite fat being the preferred/primary fuel on this eating plan.
Weight Loss from the Ketogenic Is Not From Stored Body Fat
In general, when we lose weight, it results from one of three factors: the loss of retained water, loss of muscle mass or loss of stored body fat. The ideal scenario would be to lose stored body fat.
Ketogenic diets can promote an initial loss of retained water that comes with the depletion of glycogen (storage form of glucose). This is because stored glycogen retains significant levels of water. As the glycogen levels are reduced (due to limited carbohydrates in the diet), the retained water associated with that stored glycogen is also rapidly lost through increased urination.
Although the loss of weight on a scale can be considerable in the first few days of a ketogenic diet, it will result in little loss of stored body fat. The loss of stored body fat only comes with significant calorie restriction as the body has many biological processes that help us to preserve it.
Why You Don’t Lose Fat on the Ketogenic Diet
Ketogenic diets are high in fat, which means the blood levels of fat will also be increased. As the availability of glucose in the blood decreases and the availability of fat increases, the metabolic flexibility (inherent in muscle cells) switches to using circulating fat as the preferred source of fuel for energy production (a.k.a. ATP), instead of glucose. This leads to the misconception that by getting into a state of ketosis you burn stored body fat. Instead, it is that the higher levels of dietary fat entering the blood stream are now becoming the preferred source of energy.
Furthermore, a ketogenic diet being low in carbohydrates lowers insulin levels so less of that circulating fat can be stored in adipose tissue for long-term storage. Protein can also increase insulin levels resulting in circulating fat being transported into the adipose tissue for storage. This is why eating a high-fat diet containing excess calories, but with adequate levels of protein would not result in any fat loss, even though the carbohydrate content of such a diet can be.... read more