Some kinds of sugar, it turns out, make us lose all willpower when it comes to fattening food.

A recent study by Kathleen Page and colleagues found that a dose of fructose in your drink may make you yearn for snacks. A slug of glucose, on the other hand, leaves you feeling full, food-resistant, and craving-free.

Fructose and glucose are simple monosaccharides which are often found together in nature–in everything from honey and maple syrup to fruits and vegetables. Bound together–a molecule of fructose plus a molecules of glucose–they form the disaccharide sucrose, commonly known as table sugar. Chemically this sugary pair looks a lot alike– but it turns out that their tiny molecular differences lead to major physiological effects.

In Page’s experiments, 24 volunteers guzzled