Any food -- including apples -- can make you gain weight if you eat more than you burn each day. In fact, apples contribute healthy calories if your goal is weight gain. But if you watch total caloric intake, apples are more likely to help you lose weight than they are to be responsible for extra pounds. The star ingredient is fiber, which makes you feel full, keeps blood sugar balanced and goes a step further. The fiber in apples may change gut microorganisms in ways that support weight loss.
Calories and Weight Gain
When it comes to weight gain or loss, it’s all about calories consumed versus calories burned for energy. One medium apple with its skin has 95 calories. That's enough to lead to weight gain if you consume all your calories for the day, then have an apple for a snack. Even though it’s a healthy snack, if you eat 95 extra calories every day, you’ll consume 475 excess calories by the end of one week. At that rate, apples could cause a 1-pound weight gain in two months.
If you’re following a low-carb diet, it’s important to know that all of the apple’s calories come from 25 grams of carbohydrates. There isn’t one standard definition of a low-carb diet, but 130 grams is the minimal number of carbs you should get daily, according to recommendations from the Institute of Medicine. Based on this daily intake, one medium apples fills nearly 20 percent of your total carbs for the day.
Fiber Fights Weight Gain
One apple with the skin has 4 grams of fiber, but you’ll lose half the fiber if you don’t eat the skin. Fiber absorbs water, so it takes up more space in the stomach and makes you feel full. It also makes food move more slowly through the digestive tract, so you feel full for a longer period of time. The soluble fiber in apples delays secretion of the hormone ghrelin, according to Current Obesity Reports in June 2012. Since ghrelin makes you feel hungry, this delay helps you resist eating.
Even though the carbs in apples include 19 grams of sugar, the presence of fiber ensures they’re digested and absorbed at a slow and steady rate. As a result, apples don’t spike blood sugar. Keeping blood sugar stable prevents swings from high to low, which means you won’t get hungry and overeat due to low blood sugar. It also stops high levels of blood sugar from being stored as fat.
The glycemic index rates carb-containing foods according to their effect on blood sugar shortly after eating. It uses a scale from zero to 100, with zero representing foods that don’t affect blood sugar; 100 represents the huge spike caused by pure glucose; and any score below 55 has a small effect. Apples fall in the low-glycemic range, with a score of 38.
Apples Affect Weight Via Gut Microorganisms
The soluble fiber in apples becomes food for bacteria that live in the large intestine. It turns out that this may help you lose weight. Microbes in the large intestine of people who are overweight are imbalanced, which contributes to inflammation, metabolic disorders and obesity. Fiber and other non-digestible compounds in apples -- especially Granny Smith apples -- shift the balance of microorganisms to a healthy state, which may contribute to weight loss, according to a study published in Food Chemistry in October 2014.
While more research is needed to determine exactly how fiber and gut microorganisms influence weight gain and other diseases, a group of experts from Sweden discovered that the microbiota affects amino acid metabolism, reported Molecular Systems Biology in October 2015. Using laboratory mice, the group found that some bacteria in the intestine consume glycine. This may be one connection between gut bacteria and weight, as levels of glycine are low in people who are obese, reported Professor Jens Nielsen in an article published by Science Daily.
Energy Density for Weight Management
One way to lose weight is to reduce calories by simply eating less food. While this method works, you’ll end up feeling hungry and then you may be tempted to break the diet. But if you choose foods with a low-energy density, you can eat more, feel full and still cut calories. Energy density is determined by the number of calories in one gram of food, so low energy-density foods have fewer calories per gram. Foods that are high in water and fiber are low in energy density because they add bulk to food without contributing calories.
Like many fruits and vegetables, apples help manage weight because they're packed with water and fiber. One medium apple weighs 182 grams, including 156 grams of water, which makes it about 86 percent water. Additionally, 4 grams of fiber represent 16 percent of women’s recommended fiber intake of 25 grams daily and 10 percent of the 38 grams of fiber that men need each day.
Using Apples on a Weight Gain Diet
When you're on a weight-gain plan, the simplest way to use apples to boost calories is to eat them for snacks between meals and in the evening. Three apples add 285 nutrient-rich calories. But with a goal of adding pounds, there are other ways to use apples and increase calories while keeping your eating healthy.
Another simple snack is to spread peanut butter on apple slices, then add granola. You could also slice an apple into a bowl and top it with vanilla yogurt, wheat germ or nuts, and other berries. Apples make a good flavor match with turkey, so try a sandwich with whole-grain bread or pita and other veggies.
Apple-based smoothies and shakes are a healthy option, plus you can significantly boost calories by adding a scoop of protein powder. Apples, bananas and orange juice make a classic smoothie; replacing the juice with frozen yogurt and milk turns it into a shake. You'll end up with about 300 calories per serving before adding protein powder, which contributes another 100 to 200 calories or more, depending on how much powder you use. Add nutrients, flavor and more calories with different combinations of grapes, pears, berries and carrots.