Another program called the 5:2 Fast Diet involves eating 5 days a week and fasting for the other 2 days, when women can get no more than 500 calories and men no more than 600. That’s a quarter of the amount you likely eat on the days when you don’t fast. Whether you eat those calories in one sitting or spread them across micro-meals throughout the day is up to you.
Aude, Y., A. S, Agatston, F. Lopez-Jimenez, et al. “The National Cholesterol Education Program Diet vs a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat: A Randomized Trial.” JAMA Internal Medicine 164, no. 19 (2004): 2141–46. doi: 10.1001/archinte.164.19.2141. jamanetwork.com/journals/jamainternalmedicine/article-abstract/217514.
There are three instances where there’s research to back up a ketogenic diet, including to help control type 2 diabetes, as part of epilepsy treatment, or for weight loss, says Mattinson. “In terms of diabetes, there is some promising research showing that the ketogenic diet may improve glycemic control. It may cause a reduction in A1C — a key test for diabetes that measures a person’s average blood sugar control over two to three months — something that may help you reduce medication use,” she says.
If you need to eat more or fewer calories per day, you can adjust accordingly by simply taking out or adding a bit more of the ingredients already included in a recipe. For example, adding/removing a tablespoon of olive oil or butter will add/remove about 100 calories. If you like or dislike certain recipes, feel free to shift things around. Make sure to keep an eye on the calories so you’re still falling within an acceptable range of your daily goal.
In terms of weight loss, you may be interested in trying the ketogenic diet because you’ve heard that it can make a big impact right away. And that’s true. “Ketogenic diets will cause you to lose weight within the first week,” says Mattinson. She explains that your body will first use up all of its glycogen stores (the storage form of carbohydrate). With depleted glycogen, you’ll drop water weight. While it can be motivating to see the number on the scale go down (often dramatically), do keep in mind that most of this is water loss initially.
If you want to lose weight, consider starting by avoiding sugar and starch (like bread, pasta and potatoes). This is an old idea: for 150 years or more there have been a huge number of weight-loss diets based on eating fewer carbs. What’s new is that dozens of modern scientific studies have proven that, yes, on average low carb can be the most effective way to lose weight.