The idea behind intermittent fasting is that by restricting food, our bodies will more quickly and efficiently tap our fat stores for energy. While glucose from carbohydrates is our most direct fuel source, we burn fat for energy when glucose isn't available. This happens even more during times of food deprivation.
The most common fasting window among users (64.9%) is 11-15 hours, with a fat-burn rate ranging from 37 to 42%. A popular method of intermittent fasting is the 14:10 ratio, in which you fast for 14 hours and consume all your meals in a 10-hour window.
When you fast, your body has to find an alternate source of energy since it's not getting energy from food. The body turns to stored fat to provide energy during the fasting periods, which causes the body to burn fat and leads to weight loss.
Early fasting reduces amount of abdominal fat
Upon analysis, Ruiz and his team found that all fasting groups, regardless of the time-restricted fasting method, had more weight loss — on average 3-4 kg — compared to the usual treatment group.
Mostly, losing weight is an internal process. You will first lose hard fat that surrounds your organs like liver, kidneys and then you will start to lose soft fat like waistline and thigh fat. The fat loss from around the organs makes you leaner and stronger.
What is the most effective fasting time window? Fat burning typically begins after approximately 12 hours of fasting and escalates between 16 and 24 hours of fasting.
Aerobic exercise includes any activity that raises your heart rate such as walking, dancing, running or swimming. This can also include doing housework, gardening and playing with your children. Other types of exercise such as strength training, Pilates and yoga can also help you lose belly fat.
For those aiming to lose belly fat, the 16/8 method is often recommended as the best intermittent fasting window to lose belly fat. By fasting for 16 hours and eating within an 8-hour window, you give your body enough time to burn stored fat while still allowing for a manageable eating period.
Potential Drawbacks of Intermittent Fasting
If you're not already used to skipping meals or not eating for an extended period of time, the hunger and fatigue that can occur when starting IF can be difficult to handle. Other side effects can include insomnia, irritability, headaches, and nausea.
While both 12-hour and 16-hour fasting can promote fat burning, it's possible that a 16-hour fast may be more effective. This is because the longer fasting period may lead to a greater depletion of glycogen stores, which can trigger higher levels of fat burning.
You may need a longer or shorter eating window, or you may want to try out a new protocol entirely. Decrease (or increase) your calorie intake within your fasting window. Aim for 7–9 hours of sleep. Cut back on processed foods.
FAQs. Does fasting still count when you're sleeping? Fasting is the practice of abstaining from food, so it doesn't matter what you're doing as long as you're not eating. You can still benefit from fasting even if the majority of your fasting period is while you're asleep.
The Science of Fat Loss
Think of it like a balloon losing air—it deflates, but doesn't disappear immediately. Over time, your body adjusts, but the jiggly feeling can be a temporary step along the way.
Fasting triggers a process known as lipolysis, where the body begins to break down and burn fat for energy, instead of relying on glucose from food. This can lead to significant weight loss, especially around the midsection where stubborn belly fat tends to accumulate.
Your body may go into ketosis after just 12 hours of not eating, which many people do overnight before they "break fast" with a morning meal. (A midnight snack obviously sabotages this process.) A keto diet keeps you in ketosis for much longer time periods because you avoid carbohydrates, which supply glucose.
When you exercise in a fasted state your glycogen stores are already depleted. If your workout for the day involves heavy lifting, you can do so in a fasted state, but you should prioritize eating a meal directly following your workout.