Brief Answer:
proper diet and exercise

Detailed Answer:
Hello,

loosing weight requires taking less calories than the ones you're using for your activities. One thing to keep in mind is that you can't loose weight from any particular site only, that is you can't shrink your belly only, you're going to loose fat from all sites of fat deposition.

A general advice is to avoid food that has too many calories like sweets or food with high fat content (cakes, biscuits, etc). Smaller, more frequent meals may help to reduce hunger and reduce the daily caloric intake. A dietitian may help you make a diet plan adjusted to your needs by calculating the necessary caloric intake for your body.

Physical activity is very important because it increases caloric expenditure and helps to keep the body in better shape overall. Aerobic exercise seems to be the best for weight loss programs. The amount of exercise should be adjusted to your fitness levels. For unfit individuals, walking is great. You should make sure that you don't do too much from day one. Gradually increasing the amount of exercise will help to avoid injuries.

There are certain drugs that may accelerate weight loss but I wont' recommend any. It's better if you do it the natural way. Drug assisted weight loss might be necessary for some individuals but I would advise you to avoid them.

Finally if you find it difficult to loose weight with caloric restriction and physical activity, you should ask your doctor for assessment. Certain disorders may prevent weight loss, like hypothyroidism for example.

I hope you find my comments helpful!
Kind Regards!

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