There's a reason so many people lose weight on a low-carb diet [1], including shedding stubborn belly fat [2]. "Those who eat high-carbohydrate diets, particularly diets high in processed, simple carbs, are prone to fat accumulation around the abdominal region," Gabby Geerts, a registered dietitian at Green Chef [3], told POPSUGAR. So, while you can't specifically target belly fat [4], reducing your carb intake [5] may prevent you from putting on more, while bolstering your metabolism so you can lose weight and keep it off [6]. Here, experts explain the connection and how to cut carbs effectively.
What Causes Belly Fat?
While a number of factors can contribute to belly fat [8] — including stress and poor sleep — carbs may play a role, depending on your diet. "Carbohydrates are the main source of energy for the body, broken down and utilised as glucose by our cells," Gabby said. "If you consume more carbs than necessary, your body will convert glucose to glycogen, a storage form of energy. If you consume so many carbs that even your glycogen stores are at maximum capacity, the body will then convert this to fat."
Insulin, the hormone that helps transport glucose to the body's cells, also becomes less effective if you eat too many carbs. This means if you continually eat a high-carb diet, you'll need more insulin to manage that workload, a condition known as insulin resistance [9]. "As insulin efficiency continues to decline, more energy will be stored as fat," Gabby explained.
So, if you think your carb intake could be to blame for you carrying extra weight in your middle [10], take a look at your diet, noting how frequently you eat carbs, what types of carbs you eat, your portion sizes, and what else is on your plate. "Adding a fat and protein will help slow the absorption and maintain more stable blood glucose levels," Gabby said.
Does This Mean Cutting Carbs Reduces Belly Fat?
While you can't spot-reduce fat, scaling back on carbs is often helpful in jump-starting weight loss. A low-carb diet focuses not only on reducing carb intake, but also replacing simple carbs with complex or "good" carbs [12], such as vegetables and whole grains, which are high in starch and fibre and low in sugar. It takes longer for these polysaccharides to be broken down, because multiple saccharide chains (in this case, chains of starch and glucose) are linked together. "This longer metabolic process keeps insulin secretion and blood glucose levels steady," Gabby said, which prevents excess glucose from being stored as fat.
This is compared to simple carbs, like processed or packaged foods and refined grains such as white bread, which are lower in fibre, higher in sugar, and digested more rapidly.
What Should You Eat on a Low-Carb Diet?
The number of carbs you should consume on a low-carb diet [14] varies from person to person. "Most dietary guidelines recommend that 45 to 65 percent of your daily food intake come from carbs," Phil Catudal [15], an NASM-certified trainer and author of Just Your Type: The Ultimate Guide to Eating and Training Right for Your Body Type [16], told POPSUGAR. When cutting carbs, Gabby recommends keeping that number below 40 percent and using a food journal to help stay on track. "If you eat 1,800 calories a day, 720 calories or less should be from carbs, which equates to 180 grams of carbs (four calories per gram)," she said. This formula can help you determine how many calories you should eat [17] each day to lose weight.
Both Phil and Gabby suggest focusing on healthy carbs and reducing or eliminating simple carbohydrates and added sugars to start losing fat, increase your energy levels, and stabilise your blood sugar. You may find that you need to limit even virtuous carbs like fruit [18] and whole grains in order to maintain that healthy carb count. (Fruit, for example, has a high concentration of fructose, a naturally occurring sugar.) "Make sure you understand serving sizes correctly, so you don't overindulge," Gabby said. And since both of these food groups are solid sources of fibre, "incorporate fresh vegetables and legumes into a low-carb diet to ensure adequate fibre intake and prevent gastrointestinal distress," she added.
Phil explained that cutting carbs may simultaneously drop the number on the scale, but the initial weight loss will likely be water and glycogen, the energy that's stored in the muscles after digesting carbs. Lower your carb intake slowly, starting out with 45 percent of your calories coming from carbs and stepping down from there, and monitor how your body responds. You may lose weight at a slower pace, but you'll be losing more fat than water weight.