When you eat a meal, your body spends a few hours processing that food, burning what it can from what you just consumed. Because it has all of this readily-available, easy to burn energy (thanks to the food you ate), your body will choose to use that as energy rather than the fat you have stored. This is especially true if you just consumed carbohydrates/sugar, as your body prefers to burn sugar as energy before any other source.
16-hour fast (aka 16:8): The most popular type of intermittent fast, the 16-hour fast encourages you to eat all of your meals in an 8-hour window, such as noon to 8pm. To activate the full benefits of intermittent fasting, try an 18-hour fast, once you’ve adapted to 16 hours. This would mean eating between noon and 6pm or between 2pm and 8pm. Simply avoid eating after dinner, and skip breakfast in the morning. Limit carbs to dinner.
A 2018 review of intermittent fasting in obese people showed that reducing calorie intake one to six days per week over at least 12 weeks was effective for reducing body weight on an average of 7 kilograms (15 lb); the results were not different from a simple calorie restricted diet, and the clinical trials reviewed were run mostly on middle-aged women from the US and the UK, limiting interpretation of the results. Intermittent fasting has not been studied in children, the elderly, or underweight people, and could be harmful in these populations.
There’s a ton of incredibly promising intermittent fasting (IF) research done on fat rats. They lose weight, their blood pressure, cholesterol, and blood sugars improve… but they’re rats. Studies in humans, almost across the board, have shown that IF is safe and incredibly effective, but really no more effective than any other diet. In addition, many people find it difficult to fast.
Second, fasting seems foreign to many of us simply because nobody talks about it that much. The reason for this is that nobody stands to make much money by telling you to not eat their products, not take their supplements, or not buy their goods. In other words, fasting isn't a very marketable topic and so you're not exposed to advertising and marketing on it very often. The result is that it seems somewhat extreme or strange, even though its really not.
I would like to know what led you to the conclusion to recommend eating in the morning and fasting in the evening instead of the other way around. You do not link any studies here that show TRF in the morning is better than TRF in the evening. You do state “Nighttime eating is well associated with a higher risk of obesity, as well as diabetes.” but I would hazard a guess that alot people that snack into the evening have many other factors at play that could effect their risk of obesity and diabetes and are possibly not fasting at all. I have been doing TRF from 12-8pm every day for almost a year and have seen vast improvements in my health, not least of which is a loss of 70 lbs, so it seems odd to read items 3 and 4 on your 4 ways to use this information for better health. If you have evidence that supports the idea that TRF in the evening is bad then I would like to see it and perhaps change my dieting habbits.
Black coffee won't break your fast or take you out of ketosis. In fact, according to a report published in the Journal of Basic and Clinical Physiology and Pharmacology in 2017, caffeine may even increase your metabolism, which will help promote weight loss. Black coffee also helps curb your appetite, which can make getting through your morning fast much more manageable.
Now if you're not used to drinking your coffee black, don't despair. There are some no-sugar options that can help lighten and sweeten your morning cup of joe. If you're like me and can't fathom the idea of drinking black coffee, consider adding a few splashes of unsweetened almond or coconut milk. Cutting out the sugar can be especially hard for some people, but there are sugar-free substitutes on the market, such as stevia, erythritol, or xylitol, that can serve as a great alternative. Another modification you can make in your coffee during IF is to consume bulletproof coffee. Simply by adding high-quality grass-fed butter and MCT oil, you may find yourself having a much easier time abstaining from food.
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.)
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.
I dont think this test presents the whole picture. Dairy products can spike insulin levels based on the protiens (not the carbs) in dairy products, without raising blood glucose. When intermittent fasting, part of the benefit is to take insulin out of the picture during the fast. You could be increasing yur insulin levels using dairy products but not see a change in blood glucose.
AN IMPORTANT CAVEAT: Intermittent Fasting can be more complex for people who have issues with blood sugar regulation, suffer from hypoglycemia, have diabetes, etc. If you fit into this category, check with your doctor or dietitian before adjusting your eating schedule. It also affects women differently (there’s a whole section dedicated to that below)