Keeping a food diary helps you know how many calories you consume everydayKeeping a food diary helps give you an accurate picture of what you eat every day. It may be a good way to gain more control over your diet and give you some insight into what you're eating and how it affects your health and lifestyle. For example, if you have indigestion or another medical issue, keeping a food diary may help you figure out what ingredient might be causing the problem. In addition, a food diary may help you manage or lose weight or help you eat healthier. Start jotting down a few notes about your diet and you may be surprised at what you learn.