I've been trying to diet for over two years. My goal is to lose about 25 pounds, but the most I've been able to get is 15, and I can hardly keep it off. I concentrate on eating very little and since exercise is so hard to keep up, I pretty much starve myself to death. I manage to maintain the weight for a month, and then I lose control again. I've been thinking about the various diet products in the market, such as diet teas, herbs, meal- substitution shakes, and other medical products. I'd like to know what kind of side-effects they have, and how effective they are. (Some boast a seven-day plan, but that seems hardly believable.) Also, I'd like to know how well-researched the information is on these products (i.e., are they long-term enough to cover all the side-effects?) As for aspartame, is it really harmless, or is it just not researched yet?

I am a female, five feet tall and about 127 lbs. I am not satisfied with my size. I am not obsessed with weight but with the way I look. I am very strong and have plenty of muscle. It just happens to be covered by a thick layer of fat. Yes, it runs in my family. On my father's side everyone has trouble with their weight.

I am writing to you because I don't understand why I am not losing weight. I am a vegan. I have no dairy products and no fat content in my diet. Except for the occasional pat of margarine and fried falafel, I don't see why I haven't lost weight because I just cut the dairy products out about two months ago. I have been a vegetarian for 9 years. I ride a stationary bike twice a week in my target heart rate zone. I work out with weights and do calisthenics in my room every night. What is wrong? Is there another factor I am not considering? Glands? Do I just need to be patient? I like being big, I just don't want it all to be fat.

Thank You.

Is there any danger to taking ephedra (ma huang) for weight loss?

I'm a 22-year-old woman. Many of my friends in their late 20s and early 30s (and older) have been warning me about an inevitable metabolism slow-down and subsequent weight gain around my 30th birthday. They say, "You just wait. When I was your age, I sat around all day eating pizza and I never gained a pound. Now I can't lose weight no matter what I do."

I am sure there's some truth to this, but I DON'T sit around eating pizza all day. I run three to four times a week and eat very healthfully. Will these habits ease the slowing down of my metabolism? Or should I expect some weight gain no matter what I do (as they say will happen)?

I am 18 years old and I am determined to lose a few pounds and tone my body by the end of May. I just began running and I'm starting off by running a mile and hope to work up to a four-mile run four or five days a week. My diet is generally a bowl of cereal in the morning, and a turkey or ham sandwich with some type of fruit and a bottle of water. Dinner is something different every day, but usually healthy. I also have been doing an ab workout for about seven minutes after I run. Is what I'm doing effective? What are your suggestions?

I have a job that is largely sedentary — mostly sitting in an office in front of a computer. My partner's work is very physically active. Since we've been living together, food and nutrition have increasingly become a source of stress and conflict. He needs big meals with lots of protein and calories, and I need better portion control with lots of vegetables. We're having real problems with shopping and menu planning. Since we've been living together, I've been gaining weight and he's been losing! Can you give us any advice or direct us to information on how to live and eat together while addressing both of our nutritional needs?