Massage navel can promote effective rapid defecation, and this effect is still there. And massage navel is also good for health, because navel is the only body acupuncture point we can see. So I often massage my navel. For people with sub-healthy abdomen, people with poor qi and blood, people with menstrual pain and constipation, you can choose to massage navel and abdomen to promote circulation.
If you want to lose weight by massaging your navel, it is actually more difficult. If you massage your navel to lose weight, but you eat a lot and don't exercise, then more fat will naturally accumulate in your abdomen, and such weight loss is ineffective. You must start with diet and exercise, improve your eating habits, increase your exercise, and keep the balance between your daily food intake and metabolism, so that you can feel that you are losing weight every day.
It is more effective to eat less and exercise more to lose weight in the long run. In order to make yourself healthier, you must develop good living habits.