Can I lose weight through diet alone?

This is a tough question to answer not knowing much about you. It is certainly true that some people are able to control their weight on diet alone, and do not exercise much at all. However other people have very little success with weight loss without exercise. Either way, you will have a lot more success with maintaining a healthy weight if you find an exercise that you can tolerate doing a few times per week. The key principle to keep in mind when thinking about weight loss and weight gain is calories consumed vs calories burned. The balance of these two is what needs modified if weight loss is to be achieved. Eating lower calorie foods will help the calories consumed side of the equation, exercise helps the calories burned side. Thus if you are able to consume less calories than you burn without exercising, then you will lose weight. I think the next best step is for you to schedule an appointment with your primary care physician. He or she can review your weight loss plan and make changes that would be in your best interest. In addition, you can get a referral to a nutritionist who can review your diet and tell you what you need to add or cut out to increase your chances of healthy weight loss.