How does sugar intake cause weight gain?

Sugar provides on average 4 calories per gram without any nutrients. Added sugar in your diet may provide excess calories of which will be stored in the body as fat. Strive for energy balance and a healthy weight by choosing nutrient dense foods most of the time including whole grains, fruits, and vegetables, healthy fats such as olive oil and protein sources such as lean meats, nuts, legumes, beans, soy or dairy without added sugar.

Sugar does not cause weight gain. Overconsumption of calories causes weight gain, and sugar does add excess calories. Sugar adds extra "empty" calories. "Empty" calories are calories that offer no nutritional value. I recommend that you keep your sugar intake to a minimum. Candies, sodas, sugary drinks, doughnuts, ice cream, and many other products are loaded with sugar. You can have some sugar every once in while, but try to keep your intake to a minimum. Sugar is not essential in your diet. So keep it at a minimum. Your diet should contain fruits, vegetables, whole grains, lean meats, and unsaturated fats.

Excess calories from any type of food can cause weight gain. Sugar only has 4 calories a gram. However, a 20 fluid ounce bottle of soda can have 325 calories. Over time this amount of soda, energy drinks, or sports drinks could cause weight gain. Added sugars make up around 16 percent of the total calories in American diets. If you are trying to lose weight, make sure that you get important nutrients from milk before spending excess calories on sweetened beverages.

Sugar comes from many foods, including sugary snacks such as cookies, cakes, pies, or white bread, rice or pasta. These foods provide very little nutrition, and people tend to overindulge in them. If you consume an additional 500 kilocalories per day from these items (approximately 5 cookies) these foods can lead to a 1 pound weight gain per week. 

Aside from the calories it contains, sugar is a highly addictive substance. Some argue it is as addictive as drugs like heroin. When we eat sugar, it causes a neurotransmitter response that makes us feel good, and we experience a mild "high". Once this feeling subsides, we end up craving it again. Studies are even showing that, like drugs such as heroin, we build up a tolerance to the sugar and end up needing more and more to produce that same high. Therefore, the calories add up and we end up gaining weight.

Anything in excess can lead to weight gain. Consuming sugar in moderation is not the problem. The problem arises when people overindulge in high sugar foods, which tend to make you crave more sugar. Speak with your dietitian about how you can cut back on your sugar intake.