It is not clear whether you are actually suffering from abdominal bloating or simply have what is known as a “stomach bloating”. It is important to distinguish between the two, as they are caused by different factors and must be addressed using different measures. From your description, it sounds more likely to be the latter, which is simply an accumulation of fat. This may seem impossible to you because of your relatively normal, healthy body weight, but that is only one aspect. Your body weight gives you no indication of how much fat there is in your body and how much muscle. If there is very little muscle and a relatively disproportionate amount of fat, you are quite likely to have an overall slim appearance, but have fatty deposits in certain areas. Fat is not distributed equally all over the body – we tend to accumulate fat in areas such as the hips, buttocks, and abdomen. This is probably why your arms and legs are slim, but your belly appears large. If you continue to gain weight, it might be more noticeable on your arms and legs, but your belly will probably increase disproportionately, as will your hips and buttocks.
As bad as this may sound, it is not really that terrible. You don’t seem to have much excess body fat, and with a sensible diet and some regular exercise, your abdomen should be flat again in no time. First of all, with regard to your diet, remember that it is not necessary for you to take any extreme measures. Just be a little more careful about what you eat and after eating it. You can eat pretty much whatever you want, but if it is high in fat or in sugar, you need to cut down on it a bit. Many foods are available in low fat versions today, and whenever possible, you should choose these substitutes. Also increase your intake of fruits and vegetables – fruits are especially important, because they can be used as quick, tasty snacks between meals. Contrary to what you may have been told for years, snacking is not harmful, as long as it is not done compulsively of course. A healthy snack after eating meals is a good thing and in fact several small, light meals over the course of the day are better than two or three large, heavy meals. Finally, start spending at least half an hour a day on some intense physical activity that you enjoy.
In case you actually are suffering from abdominal bloating and not accumulated fat, you should consult a doctor.