First, McDonald's offers some low-calorie and low-fat options. For example, McDonald's salads, fruits and roast chicken are all healthy choices. At the same time, McDonald's also provides some low-calorie snacks, such as small packages of French fries and apple slices. If you want to lose weight, you can choose these low-calorie and low-fat foods and reduce high-calorie and high-fat foods.

Secondly, McDonald's food can make you feel full. Because McDonald's food usually contains a lot of protein and cellulose, these substances will make you feel full, thus reducing your food intake. For example, McDonald's chicken burgers and chicken rolls contain a lot of protein and cellulose, which can make you feel full.

Therefore, if you want to lose weight, you can choose these foods which contain a lot of protein and cellulose to reduce your calorie intake.

Finally, McDonald's food can make it easier for you to control your calorie intake. Because McDonald's food usually has a clear nutrition label, you can easily know the calories and other nutrients contained in each food. This can help you control your diet better and avoid eating too many calories.

In short, eating McDonald's doesn't necessarily make people fat. If you choose low-calorie and low-fat foods and pay attention to controlling calorie intake, McDonald's can also be a good helper to lose weight. Of course, losing weight requires long-term persistence and reasonable eating habits. Whether you choose McDonald's or other foods, you need to pay attention to a balanced diet and moderate intake in order to maintain a healthy weight.