The truth about Intermittent Fasting- It can actually worsen your health.
Before we get started on explaining the dangers behind Intermittent Fasting (IF), I want to make it clear that this is NOT talking about the 8:16 daily IF schedule, where you eat only for the first 8 hours of the day of at least 3-4 meals spread out, of less than 600-700 calories per meal (depending on your daily metabolic rate). This 8:16 schedule is actually very healthy (as long as you are not combining both high fat and high carbs in a single meal- which is dangerous no matter what your eating schedule is- you can read our blog post on why that is dangerous here.), and is actually what most people should follow for the most optimum health, although a 10:14 or 9:15 schedule is also great, as long as the eating window starts in the morning, as you want to avoid eating in the evenings (within 3-5 hours of going to bed), because the body is less insulin-sensitive in the later part of the day (requiring more insulin, which means more fat storage and increased insulin resistance over time), and metabolism actually slows down late afternoon which means it's more likely to store fat with those later meals, and larger dinners are more likely to turn into fat than larger breakfasts and lunches.
The IF that I am referring to as detrimental to your health are the "eat only once a day", or even only twice a day, meal schedules, or even going an entire day without eating anything at all (that can be dangerous because it ends up slowing your metabolism and decreasing insulin sensitivity, so that when you finally do eat, your blood sugar and insulin spikes significantly, and you actually gain more weight, thanks to the slower metabolism and increase in insulin- which can be dangerous over time causing insulin resistance and diabetes, or other metabolic issues). It's not always only about "calories in, calories out".
But if your 8:16 schedule is actually that you don't eat anything for the first 8 hours of the day and eat in the last 16 hours, that actually can be detrimental as well, as skipping breakfast and eating in the last hours of your day increases insulin production and fat storage which can lead to diabetes and weight gain. So it's important that your first meal starts within 30 minutes of waking up, which jump-starts your metabolism, gives you both physical and mental energy for your day, and allows your cells to be more sensitive to insulin for subsequent meals, so that insulin is not created by your liver in excess (which is what you want to avoid, as it can cause both fat storage (even on a calorie deficit), as well as insulin resistance- a huge risk factor to all kinds of diseases today). If your body is used to skipping or delaying breakfast, it may not get hungry that early in the day, but your body can adapt over time, you just need to force yourself to eat an early breakfast even if you are not hungry, and after a week or two, your body will adjust so much to where it actually starts becoming hungry in the early morning, and then this eating schedule will become easier over time. You can gradually introduce this eating schedule to decrease digestive discomfort by starting off with a small meal or snack, and then increasing the calories of this first meal as time goes on. Eating 4 smaller meals, once every 2 to 2.5 hours, is actually even healthier than eating 3 larger meals every 2.5 to 3 hours. They are both the same amount of calories, but having less calories per meal means less insulin production and less fat storage, as well as the fact that eating more frequently keeps your digestive system running which also increases your metabolism- good news for those who have a hard time with weight loss.
People assume that eating less, like only once a day or every other day, actually means LESS insulin production, but that is far from the truth. The body actually creates MORE insulin in that one large meal eaten once per day, that it does if that same meal and amount of calories were spread out in smaller meals (such as every 2-4 hours over 8-11 hours). Not only this, but when your body goes a very long time without eating (more than 16 hours), it actually becomes less SENSITIVE to insulin, which means the body needs to create MORE insulin for that one meal, than the combined insulin produced if that same meal and number of calories were spread out over 8-11 hours. And it's the same with blood sugar response. The body's blood sugar increases MORE on average in that once-a-day large meal, and stays elevated for a longer time thanks to so much food needing to take extra long to digest and just "hanging out" in the blood stream, than the combined total blood sugar response/length, if that same meal were spread out into smaller meals. Not only this, but the metabolism decreases the longer it goes without food. The body will assume its starving, EVEN THOUGH it is consuming the same amount of calories as more-frequent smaller meals.
It is not normal, on an evolutionary basis, to eat like this, so it thinks something is wrong, and responds by going into "starvation mode", where it decreases its metabolism in the hopes to store fat. This will lower your overall energy output, you will feel tired and fatigued, lose mental focus, etc. This is called "starvation mode". This means MORE fat storage, less insulin senstivity and thus more insulin production, higher blood sugar spikes, and a much higher risk of insulin resistance and diabetes.
If you truly want to maximize your weight-loss results and decrease the risk of insulin resistance/diabetes and other metabolic disorders, read the truth here on this post.