If obese teens eat more fructose for a week — like swapping some carbs for sugary foods — but don’t eat more calories overall, it doesn’t seem to change how their body handles sugar or fat, at least in the short term.

What we've found so far is that increasing fructose intake does not appear to affect insulin or cholesterol levels in obese adolescents when total calorie intake is controlled, at least over short periods. Our analysis of the available research suggests these effects are consistent even when fructose makes up a larger portion of the diet. We looked at two key assertions based on controlled studies lasting about one week. The first assertion showed that replacing other carbohydrates with fructose — without increasing total calories — did not lead to noticeable changes in how the body processes sugar or fat [1]. This was supported by 33.0 studies. The second assertion, also supported by 33.0 studies, found that significantly increasing fructose intake under the same calorie-controlled conditions did not alter blood sugar, insulin, or cholesterol levels in obese teens [2]. Together, these assertions add up to 66.0 supporting findings and 0 refuting findings. Both point in the same direction: short-term increases in fructose, as long as total energy intake stays the same, do not seem to impact key metabolic markers in this group. We want to be clear — this is what we’ve seen so far, based on short-term studies. We cannot say what might happen over longer periods or under different dietary conditions. Also, we’re not making any claims about overall health or weight — just what the data shows regarding insulin and cholesterol. The takeaway: In the short term, swapping other carbs for fructose in a calorie-controlled diet doesn’t appear to shift insulin or cholesterol levels in obese adolescents, based on what we’ve reviewed so far.