Welcome to HCM.
It is good that you are conscious for your health at this age and you are avoiding those foods.But some amount of fat is also required for energy and to complete other metabolism
in the body.
It is better to consult dietician for better guidance for your diet plan
To keep the shape of body always try to burn your calories, for that go for exercise regularly,cycling,swimming will be surely helpful.Drink more water and fruit juices.
You can also join gym and do exercise under physio trainer.