A friend of mine and I were disagreeing about this point and I thought maybe you could help. I have heard that it is not possible to both lose fat and build muscle mass simultaneously: ideally, a person should do cardiovascular exercise with dieting to lose extra body fat, and then start to focus on building up muscle mass. He says it's possible to both burn fat and build up muscle over the same period of time. Which is the case?

I have a question about walking for weight loss. My walking buddy believes the theory of walking distance is what helps you lose weight best versus my theory that it is the speed at which you walk that matters. So, could you help me figure this one out? Which matters most in ultimate weight loss: speed or distance?

When working out in the gym, machines, such as treadmills and stationary bikes, show how many calories you are burning. Are these calculations correct, or is it just something to keep the participants happy?

After practicing yoga in normal temperatures for years, I recently attended a heated yoga class (heated quite hot: 95 to 100 degrees!). The experience left me dizzy, nauseous, and completely enervated. Afterwards, I expressed my concern to the teacher, asking why the studio needed to be so hot. She "explained" that by sweating, supposedly the body releases "toxins" and that my nausea and dizziness must indicate that I need to "detox." Personally, I think I was suffering from heat exhaustion. I've heard this silly explanation more than once, as many people seem to believe toxins are released through sweat. But is that true??? And — next question — doesn't exerting oneself in extremely hot temperatures seem like a recipe for dehydration? Are their any benefits that make it worthwhile, or is all this heated yoga just nonsense?

My friend recently got a blood test back from her doctor and she was told she was deficient in Vitamin B12. She is a vegetarian. What can she do to supplement this vitamin if she does not eat meat?

I know if I cook vegetables too long, they would lose nutrients. How about pasta and beans? Do they lose their carbohydrates and proteins and other nutrients in them if I cook too long? I always cook pasta and beans for over an hour because I like nice and soft and plumed pastas and beans. Am I eating zero nutritious pasta and beans?

Do "fat burners" really work? If so, why? If not, why not?

I was recently turned away from a blood donation site for slightly low hemoglobin. I'm a menstruating woman and a vegetarian, so it wasn't a big shock. I'm trying to add more iron to my diet in the form of beans and cruciferous veggies and eggs (cooked on cast iron!), but I've run into some confusion. The pamphlet I got from the blood bank suggests raisin bran as a very good source of iron. Several health articles and studies I've found online also point to raisin bran, but others say that wheat bran inhibits iron absorption and should be avoided when trying to raise iron levels. Sometimes the conflicting information comes from the same source! Can you shed any light on this, Alice? Would a bowl of raisin bran a day help or hurt my iron intake?

Is it bad for you to drink hard water? Can the calcium in hard water be absorbed by your body and would this be good for you, like the calcium in milk?

Does altitude affect calorie-burning? That is, if I do the exact same workout twice — once in New York City and once in Colorado — will I burn more calories at the high altitude? What things DO affect how many calories you burn in a workout?

I'm a college student and also a bodybuilder. I've become aware of very high protein intake amongst bodybuilders at my gym. I'm skeptical as to consuming as much protein (around 225 grams) a day like the bodybuilders at my gym do. Do bodybuilders need more protein? And if so, how much more?

I have recently learned that in order to burn fat as a fuel, your body requires carbohydrate. Up until this point I had been doing cardio training first thing in the morning on an empty stomach, as I had read that this is optimum for fat burning. However, now I have a small carbohydrate snack before I train in order to prevent my body using lean muscle tissue as a fuel. Today I have again read in another book that training on an empty stomach first thing in the morning burns the most fat. I am a little confused over the best thing to do! I train with weights twice a week and do cardio three times per week. I do want to maintain my lean muscle, but am looking to reduce my body fat.

What is the difference between Ionic and colloidal in vitamins & minerals?

I sometimes can't find the time to cook for weeks at a stretch. During these periods, I live on whole grain bread, cheese, and fruits (usually pears). Oh, and a couple of soft-boiled eggs at breakfast. I feel very healthy, but my friends have told me that this diet is low in minerals. Is this true? If it is, what should I add to it?

I don't really understand the way daily vitamin supplements work... I take One a Day for Women. My question is, if the vitamins you take are not time released, does your body use them the way intended or are they just a waste of time? Thanks.

Is carbohydrate transformed into fat in the body?

Is it bad to exercise while slightly drunk? Some friends like to hike and drink beer. I find that I get flushed easily, and tire more quickly. What's going on?

1) What are your thoughts regarding the use of Splenda as a sugar substitute? I have heard that the body is not able to metabolize this and that it is excreted through the urine. Do you have any current research on Splenda and the side effects? I realize it is a relatively new product. Thank you!

2) I searched the archives and found no information on Splenda or sucralose. Lately, it seems like Splenda is gaining popularity in the crowded sugar-substitute category. It seems too good to be true — measures cup for cup like sugar, you can bake with it and mix it into drinks, and it is made from sugar so it really tastes like sugar. My two questions are... is this a safe product, or are there some disadvantages with the product? And secondly, if it is very safe and versatile, why aren't more companies using it now?

I know it's necessary to have a certain amount of fat in your diet, but occasionally I hear about "good fat" and "bad fat." What is the difference? Is that the same as saturated/unsaturated? What foods have "good fat"? Can I tell by looking at the nutrition label on a food product which kind of fat I'm eating?

Is chocolate bad for you?

I am a wrestler and have very great ambitions within the sport. I lift weights for five to six hours a day, making sure I perform every set to failure often including negatives as well. In addition to working each muscle group two times a week, I make sure to give each muscle group 48 to 72 hours of rest. Recently though, I have learned that training longer than an hour a day can have a catabolic (muscle breakdown) effect on your body. This was very concerning to me because muscle-wasting during my training seems truly counter-productive, but I am also aware that a decrease in training may lead to muscle atrophy and that also poses a deep concern. I have also learned that cardio and even sleep can have a catabolic effect. I will have to cut my training time eventually due to time restrictions during the season because of school day and team practices, including traveling time and homework. I am posing a couple of questions within this letter: 1) Can I reduce the volume of my routine to about an hour and still make gains that are comparable or better to those I experience with my five to six hour workouts and if so, how? 2) Is catabolism truly a legitimate matter to be concerned with?