Your stomach capacity will be highly reduced, so you must get used to eating very small portions every so often. It will take some months until you get adapted to your diet. Initially, you will only take liquids (4-6 weeks), then mashed or pureed vegetables, and finally solids. After 6 months, you will be able to eat almost any kind of food.
You must not forget that food tolerability and the adaptation period are very variable; it is more difficult to eat some types of food such as meat, bread, rice, and fiber vegetables
Restrictive techniques require a special cooperation, because they limit more the intake of certain types of food; if you force their intake, you will vomit.
Anyway, you must restrict your calorie intake in order to lose weight gradually. Due to the surgical procedure, it will be easy for you to lose weight almost without feeling hungry, and this weight loss will be sustained over a long time.
But you must not forget that, if you eat food which is rich in calories (such as pastries or chocolate), it will be difficult to lose all the desired weight.
You will be able to return to your activities gradually. Three weeks after the procedure, you will be able to drive.
During the first weeks, you must avoid making efforts or picking up heavy objects. After 6 weeks, the wound will be healed, and you will be able to conduct your normal physical activity (going back to work).
It is necessary to start a regular program of exercise after 4-6 weeks; this will favour weight loss. You may start by walking, swimming, or riding a bicycle. It is convenient to start little by little, initially 30 minutes per day.
You must continue taking the same medication as before surgery, even though dose adjustment or change of formulation might be necessary during weight loss.
With time, it is likely that you will no longer need some of your drugs, because the conditions associated with obesity (such as diabetes, hypertension) will gradually disappear.
Vitamin and mineral (iron) supplements are typically prescribed during 12-18 months, which will be withdrawn if a varied diet is followed; in some other cases, gastric protection, fiber, and mild laxatives may be required.
With simple techniques, 30% of the initial weight is lost (30-40 Kg); with complex techniques, there is a 40-50% loss (50-60 Kg), though not everybody will lose the same weight. Typically, male patients, and those younger, will lose more weight.
Maximum weight loss will occur before the first 18 months after surgery; sometimes there is a mild re-gain after 2 years (5 to 8 kg).
You must remember that surgery success depends to a high extent on the adequate compliance of diet guidelines, and on physical exercise. A change in lifestyle is imperative.
If all this is followed, surgery will be a success, and not only regarding weight loss, but (and this is more important) you will also stop suffering many diseases which were caused by your obesity. There will also be an improvement in your mobility, resistance, your self-esteem, your mood, your personal relationships, your work capacity, your couple relationship (if it was previously good), etc.
As in any major surgical procedure, there are some surgical risks that must be assessed, known, and compared with the risks of sustained severe obesity. There are early risks (after the procedure), and late risks.