Yes, your body will burn fat before it starts breaking down significant amounts of muscle.
When it comes to weight loss, it is common for the body to burn muscle before fat. This happens because the body has a preference for using carbohydrates (glucose) for energy first. If carbohydrates are not available, the body will then turn to glycogen, which is stored glucose in the liver and muscles (1).
Fasting typically burns fat from the abdominal area first. This is because the body prioritizes burning visceral fat, which is stored around the organs in the belly, for energy when it's in a fasting state.
But your body shouldn't naturally go for muscle first in weight loss—if you're doing it right. "A person who is attempting to lose weight by not eating may lose weight in muscle first before fat," he says. How does that happen? Well, the body likes to go for carbs (glucose) for energy first.
Metabolism: Muscle tissue burns more calories than fat tissue, even at rest. Building muscle can help to increase metabolism and promote the breakdown of fat for energy, which can be beneficial for weight management and fat loss. Health: Building muscle and burning fat can have a number of health benefits.
That said, the one true way to identify whether or not you're losing muscle is to measure your body composition. The most accurate ways to measure your muscle versus fat involve some pretty fancy techniques (like x-ray scans called DEXAs or underwater weighing), says Oldham Carnes.
Unhealthy eating is the biggest driver of big bellies. Too many starchy carbohydrates and bad fats are a recipe for that midsection to expand. Instead, get plenty of veggies, choose lean proteins, and stay away from fats from red meats. Choose healthier fats in things like fish, nuts, and avocados.
Fasting can cause muscle loss, but it's normally well after 24 hours. And that's not something commonly done by those practising intermittent fasting. The process in which we "lose" muscle occurs when, in order to maintain blood glucose, our amino acids must then be converted into glucose (called de novo glucogenesis).
Fat burning typically begins after approximately 12 hours of fasting and escalates between 16 and 24 hours of fasting.
When on a weight loss journey, lack of protein is a huge culprit of muscle loss. “Our bodies don't store protein like other nutrients, so it's important to eat the right amount every day,” says Kate. “Everybody is different and will have different protein requirements.
The 16/8 method is a good starting point, where you fast for 16 hours (including the time you're asleep) and then eat during an 8-hour window each day. To ease into it, begin with a shorter fasting period, like 12 hours, and gradually extend it as your body adjusts.
Create a Small Caloric Deficit
Instead, aim for a smaller, sustainable caloric deficit of about 300-500 calories per day. This controlled approach encourages steady fat loss while minimizing the breakdown of muscle tissue. The ideal pace for weight loss should be about 0.5 to 1 pound per week.
After hepatic glycogen stores are depleted, the body uses adipose tissue and protein for energy. The liver has an active role in the metabolism of fats as it is the main oxidizer of triglycerides. In more extreme versions of fasting, where fat sources have been expended, the body breaks down skeletal muscle for energy.
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.
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.
The article highlights five homemade morning drinks that assist in losing belly fat by enhancing metabolism and promoting fat burning. These beverages include honey-infused lemon water, jeera water, buttermilk or chaas, cinnamon tea, and green tea.
The rule of thumb, Fernstrom says, is that losing 8 to 10 pounds translates to going down one size. Still, if you lose "up to 15 pounds, you may be OK in your old size," she says. But putting off buying new clothes until you really need them doesn't work for everyone.
So even though you may be losing fat, you're gaining muscle. You might feel slimmer, even as the number on the scale rises. “The scale doesn't tell the entire story,” said exercise physiologist Christopher Mohr, PhD, RD. “Since muscle and fat take up different volume, they look very different on the body.”