Table sugar and high-fructose corn syrup are about 50% fructose and these ingredients have become increasingly common in many foods and beverages. Eating too much fructose can induce leptin resistance, a condition that can easily lead to becoming overweight when combined with a high-fat, high-calorie diet, according to a new study with rats. This is the first study to show that leptin resistance can develop as a result of high fructose consumption and that leptin resistance can develop silently, that is, with little indication that it is happening.