A can of coke is around 300 kcal, if memory serves. The problem isn't the calories. It's the effect refined sugar, supplied without fiber, has on blood sugar levels, insulin secretion and glucagon resorption. They don't get to use the 300 kcal, instead, due to the composition, a good chunk of those calories are instantly stored, and all circulating fats, whether from own adipose tissue or dietary, will be absorbed too fast and stored, even though it's not necessary. Sugars trick the metabolism. Sugars without fibers are the enemy. All calories are not created equal.