One bar of milk chocolate that has 1.55 ounces or 44 grams, contains 235 calories, 13 grams of fat, 8 of which come from saturated fat, and 221 grams of sugar. One ounce of dark chocolate, or 28.35 grams, contains 156 calories, 9 grams of fat, 5 from saturated fat, and 13 grams of sugar. Saturated fat elevates blood cholesterol, which puts you at risk for heart disease and stroke. The added sugar in chocolate has no nutritional value, which can cause weight gain and heart disease, according to the American Heart Association. If you’re going to indulge in chocolate, Alice Lichtenstein, a professor at Tufts University recommends that you cut out other treats on that day or that you walk an additional 30 minutes to counteract the additional calories you’re getting.