The keto diet is one of the most buzzed-about ways to lose weight. This high-fat, moderate-protein, and super-low-carb diet has taken the internet (and Instagram) by storm, promising all kinds of health benefits including weight loss, more energy, and lower blood sugar levels.
This diet works by putting your body into a state of ketosis, where it burns fat for energy instead of carbohydrates. As your body taps into its fat reserves, this is where weight loss (and a loss of body fat) happens. But since the diet is high in dietary fat, some people may be confused exactly how to get into ketosis.
"In order to reap the benefits of ketosis, a person will need to cut carbs low enough to switch the body from using carbs to using fat," said Catherine Metzgar, PhD, RD, and a member of the clinical team at Virta Health. Although there are some supplements available that promise to increase ketones, that doesn't mean your body has actually made the switch from burning carbs for energy to burning fat, she explained.
This way of eating to put your body into ketosis is called nutritional ketosis. To get into nutritional ketosis, she said, you do need to increase your healthy fat intake, but cutting carbs is the biggest factor. "By definition, nutritional ketosis is achieved by reducing total carbohydrate intake to less than 50 grams of carbs daily," she explained, although every person has their own unique threshold for carbs and entering ketosis, so it may be a little above or below 50 grams of carbs.
However, there is another way to get into ketosis that Dr. Metzgar doesn't recommend: starvation ketosis. If the body depletes glycogen stores enough, like when you're not eating for long periods of time, it will move on to burning fat. Although many people think this can be achieved through intermittent fasting, Dr. Metzgar said you would need to fast for about a week to burn fat for fuel and enter starvation ketosis, which goes far beyond the traditional intermittent fasting methods.
She warns against starvation ketosis because prolonged periods of fasting can be dangerous, especially if you have a history of low blood sugar, are taking low blood sugar medication, or are taking blood pressure medication. Plus, it can trigger disordered eating for those who have an unhealthy relationship with food.
Ultimately, while upping your fat intake will help you achieve nutritional ketosis, the biggest component is cutting carbs.
"To get into ketosis nutritionally, fat intake does need to increase," she said. "But that doesn't mean you need to start taking shots of olive oil and eating sticks of butter. In my practice, most people need to make slight modifications to increase their fat intake, but primarily, the biggest change is cutting carbs."