High Fructose Corn Syrup (or HFCS) is a syrup made from starch and is widely used in the United States as an alternative to sugar.
Like table sugar, HFCS is composed of glucose and fructose, albeit in different proportions. 1g of HFCS has the same amount of calories as any other type of sugar (4kcal per 1 gram).
There is no scientific evidence confirming that consuming products with HFCS per se leads to unhealthy weight gains and that its impact on health is worse than that of other types of sugar.
As explained by the World Health Organisation (WHO)1, the fundamental cause of obesity is an energy imbalance between calories consumed and calories expended. Eating more calories than required by our body can lead to unhealthy weight gain. Like any other food, food containing HFCS or other types of sugars should be consumed in moderation.