If your usual diet has not included many vegetables, fruits, cereals or other products rich in fiber, it is not recommended to jump straight to the full recommended amount, especially if you want to apply a weight loss program.
Your body may simply not be ready for a normal diet and will experience shock and you may experience unpleasant symptoms such as bloating, a feeling of heaviness, etc. The reasons for this are simple, the body itself has already adapted to a not entirely healthy diet without fiber - the intestinal microflora may be weakened, the acidity may have changed or other similar reasons and it may take some time for it to adapt again.
In this case, it is recommended to start with half or a third of the indicated dose for the first couple of days, increase it when you feel that everything is fine and after a week or a little more from the start of use, switch to the recommended program, or an amount that is acceptable to you.