People often blame modern fast-food culture for obesity. These days, it's easy to overeat or eat too much fatty or sugary food. The sight of food can make us want to eat. So we eat because food is there and tastes good, not because we feel hungry. And when we eat in this way, we put on weight.^{1 2 3}

• Fast-food outlets and convenience stores are everywhere. So it's easy to eat even if you aren't particularly hungry.
• Servings are often large. And everything seems to come with "extras": extra cheese in your double cheeseburger, extra relish, extra fries. Even healthy-looking options like salads often come with dressings that are high in fat.
• Processed food often contains a lot of fat or sugar. Fat and sugar have a lot of calories. So if you eat this kind of food, you're more likely to put on weight. Even a small portion, such as a cookie, is likely to have a lot of calories.
• Most of us don't count the calories we eat.
• We're also eating more processed foods and snacks at home. These often have a lot of calories.⁴

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.