Every diet plan that has ever produced results is, at its heart, a strategy for lowering calorie intake. All-fat, no-fat, reduced-carbs, gluten-free, paleo… they may all take different approaches to weight loss, but they all have the same result. By limiting food intake, or even just limiting food options, these diets reduce our calorie consumption. And when calorie intake drops below calorie burn, that’s when we start to drop the pounds.
You’ll run out of energy. When you don’t have anything in your system for several hours, your blood sugar will eventually drop below baseline. If you’ve ever had a blood sugar crash, you know how this state feels. Sleepiness, trouble focusing, lightheadedness, intense cravings, and the occasional mood swing typically accompany low blood sugar. Your cells run low on fuel and they start demanding that you give them more carbs.
Because it simplifies your day. Rather than having to prepare, pack, eat, and time your meals every 2-3 hours, you simply skip a meal or two and only worry about eating food in your eating window. It’s one less decision you have to make every day. It could allow you to enjoy bigger portioned meals (thus making your tastebuds and stomach satiated) and STILL eat fewer calories on average.
So, if your goal is ketosis, intermittent fasting can help you get into ketosis even faster. Simultaneously, the keto diet makes intermittent fasting more doable because your body is already adapted to fasting with ketones. In addition, most people naturally eat less frequently on keto because of the high satiety level, so you’re likely already used to bigger windows without food.
After that timespan, your body goes into what is known as the post–absorptive state, which is just a fancy way of saying that your body isn’t processing a meal. The post–absorptive state lasts until 8 to 12 hours after your last meal, which is when you enter the fasted state. It is much easier for you body to burn fat in the fasted state because your insulin levels are low.
Stable blood sugar levels are vital to the success of any diet. This is because when glucose levels plummet, it leads to intense hunger, which almost always results in binge eating. Stable blood sugar levels help eliminate headaches, lack of focus, poor memory, and brain fog as well. Interestingly, these are common complaints among those who follow high carbohydrate diets, as opposed to diets that are rich in fat and protein.
Cons: On the flip side, if you have a hard time handling cheat days the healthy way, this method might not be for you. Additionally, because the plan is pretty specific and the fasting/feeding schedule varies from day to day, this method can be a bit confusing to follow. (However, the plan does come with a calendar, noting how to fast and exercise each day, which may make it easier.)
I was very curious about this, so I asked the opinion of metabolic expert Dr. Deborah Wexler, Director of the Massachusetts General Hospital Diabetes Center and associate professor at Harvard Medical School. Here is what she told me. “There is evidence to suggest that the circadian rhythm fasting approach, where meals are restricted to an eight to 10-hour period of the daytime, is effective,” she confirmed, though generally she recommends that people “use an eating approach that works for them and is sustainable to them.”
How It Works: Fast for 14 (women) to 16 (men) hours each day, and then “feed” for the remaining eight to 10 hours. During the fasting period, you consume no calories. However, black coffee, calorie-free sweeteners, diet soda and sugar-free gum are permitted. (A splash of milk in your coffee won’t hurt, either.) Most practitioners will find it easiest to fast through the night and into the morning. They usually break the fast roughly six hours after waking up. This schedule is adaptable to any person’s lifestyle, but maintaining a consistent feeding window time is important. Otherwise, hormones in the body can get thrown out of whack and make sticking to the program harder, Berkhan says.
The four-hour eating window — which Hofmekler refers to as the “overeating” phase — is at night in order to maximize the Parasympathetic Nervous System’s ability to help the body recuperate, promoting calm, relaxation and digestion, while also allowing the body to use the nutrients consumed for repair and growth. Eating at night may also help the body produce hormones and burn fat during the day, according to Hofmekler. During these four hours, the order in which you eat specific food groups matters, too. Hofmelker says to start with veggies, protein and fat. After finishing those groups, only if you are still hungry should you tack on some carbohydrates.
Intermittent fasting (intermittent energy restriction or intermittent calorie restriction) is an umbrella term for various eating diet plans that cycle between a period of fasting and non-fasting over a defined period. Intermittent fasting is under preliminary research to assess if it can produce weight loss comparable to long-term calorie restriction.
For this reason, certain experts believe that intermittent fasting improves a broad range of neuro-degenerative conditions, including stroke, Huntington’s disease, Parkinson’s disease, and Alzheimer’s disease. After conducting a study on animals, researchers at the National Institute on Aging, found that cyclical fasting helps neurons in the brain to resist degeneration and dysfunction.