My soccer coach is suggesting we eat bananas at half-time of our soccer game to rebuild our energy for the second half. I understand that bananas are a very good source of energy, among other things. I don't see any detriment to this idea, but my question is this: Does the consumption of bananas result in an immediate energy boost? I have always been led to believe that food must be digested through the system before the body realizes the benefits, and that usually takes several hours. Can you enlighten me?

Why is it I can always run a greater distance on a track than I can on a treadmill? On a track, I can run five or six miles, but on a treadmill, I can only go a maximum of three or four, then I tucker out. Is it because I get more bored on a treadmill, or is there a more physical explanation?

Is egg powder an effective egg substitute for protein?

How can you tell when you're full? I am not over-weight, but I tend to over-eat. How can I know when to stop?

I have been chewing and spitting large amounts of food (pretty much always sweet stuff — pastries, chocolate, etc.) almost every night for eight or nine months. I am eating a healthy, balanced diet otherwise, maybe a little on the lower caloric side (1300 to 1500 calories per day). My chewing and spitting sessions usually follow a balanced meal. I know this is a type of eating disorder. I have done a lot of research online and I know that there are side effects, although they vary depending on who you ask. Some sites mention that chewing and spitting activates the release of insulin and results in hyperinsulinemia, insulin resistance and weight gain. Is this true? How long would it take to develop these problems? Are these reversible if I were to stop this behavior?

Are there other types of eating disorders other than anorexia and bulimia? For example, I have this fear of unnecessary fat in food and eat everything "plain," that is, without butter, oil, dressing, or sauce, etc. I thought that it's good that I'm this health conscious, but my friends say that it's a little obsessive. Is this an eating disorder?

I'm curious to know if going to the gym increases sexual drive? I am a female in my 20s and recently started an exercise routine (running and weights), and I have noticed that my sexual drive has increased significantly. There have been no other major changes in my life, and I have been dating the same man for close to two years now, so I can think of no other real reason why my libido would have increased. Is there any real connection between working out in the gym and beneath the sheets?

I realize dessert products labeled fat free are high in sugar (which can be converted into fat). But which is the lesser of the two evils: high fat or high sugar content?

I know that plants (besides soy) are considered "incomplete" protein sources, because they don't contain all of the essential amino acids. However, why is it that the nutrition facts of many grains and vegetables say they have protein? For example — a serving of pasta has seven grams of protein, corn has twp grams, and chickpeas have six grams. Is this considered "incomplete" or "complete" protein, and how can you know how much complete protein you are eating when you mix, for example, a serving of corn, and beans? I think average people should eat 50 to 60 grams of protein a day, but how can you ever know how much you are really eating if you are mixing incomplete proteins that together contribute to your day's protein requirement?

I frequently hear that beverages with caffeine or alcohol are not good for replenishing fluids and preventing dehydration. But in reality aren't they just a bit less effective at hydrating your body than other beverages? In other words, if you were stuck in the desert with nothing to drink but beer, coffee and cola, would you actually be worse off and die of thirst sooner if you drank these beverages versus not drinking anything at all?

Dolomite is a balanced source of calcium and magnesium. Why is it not commonly offered as a nutritional supplement?

I've heard of body suits that increase sweating during exercise. Then I heard that Saran wrap had the same effect. I want to shed pounds but first I wanted to know if wrapping plastic wrap around the stomach helps burn fat during exercise.

You've been a hero(ine) of mine for quite some time. I hope YOU can answer this question (it seems no one else can).

I've been reaping the benefits of green tea for about a year now, and I feel great! Just recently I began opening the tea bags after brewing, and putting the tea leaves in with the actual brew and drinking the leaves as well. Does this add more health benefits to green tea? I would think so! So far, no one has been able to answer this question directly. Please let me know if you know!

Stay Awesome Alice! May your boards hum forever!

What is the best way to prepare, health wise, before a big test such as the SAT, LSAT, MCAT? What foods do you recommend to keep my "brain moving?"

Does cooking in a cast iron skillet supply any iron to your system? My husband and I have a disagreement.

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 have heard that if you exercise/work out in the morning before you eat breakfast that it will cause your metabolism to increase throughout the day, helping you to burn calories. Is this true?

I've read a lot lately about midnight snacking and late night eating and obesity and calorie worries, but my problem lies in the opposite direction — I'm LOSING weight, and insatiably hungry, day and night! The only advice I get is, "Eat healthy," which is preaching to the choir, since I consume more fresh produce, mostly vegetables, and home-cook all my own meals. At a recent nutrition check-up, the nutritionist patted me on the back in congratulations for having one of the healthiest lifestyles he's seen, and shrugged at my inexplicable hunger. The fact is, I'm in the kitchen every other hour, and my body doesn't differentiate between awake and asleep anymore when it comes to hunger. I go to bed on a full stomach, and wake up every three hours to eat again. It's exhausting! I'm falling asleep during the day — but never more than an hour, because hunger strikes. And amid all this, my grocery bill climbs and my weight drops. I don't get it. What am I doing wrong?

I just checked serving sizes for different kinds of nuts, and it turns out that I eat 500 to 1,500 calories worth of nuts every day. I eat a couple of different types (almonds, peanuts, cashews) and nut butters. I've never had a problem with this; I'm on the thinner size of average and feel relatively healthy. I know nuts are healthy for you, but can they be too much of a good thing?

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 try to eat a piece of fruit for dessert after a meal; however, when I have substituted after-meal sweet cravings with fruit, I still end up craving some other type of sweets (i.e., candy, chocolate, ice cream.) It seems that after every meal, I can't feel satisfied until I have eaten something of this food category. I do try to listen to my body and this appears to be programmed into my mind telling my body it is wanting this food consistently. Can you provide any explanation as I am trying to lose weight and this type of food is empty calories and unhealthy? I work out six days a week and have recently given up smoking.

I get the apples provided in the dining hall on campus every day and have noticed that they are completely coated with wax (scratching the surface produces white flakes). I was wondering, how harmful is the wax if I eat two or three apples a day?

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?

What are the advantages of eating five or six smaller meals per day, as opposed to three meals per day? I've heard it helps to lose body fat. Also, are there advantages to eating more of your calories early in the day?

1) A friend and I were discussing this. We both try to stay healthy by eating well (high fiber, low fat, lots of veggies, fruit, etc.) and living an active enough lifestyle (hiking, rock climbing, biking, etc.) that we stay in shape. The question we have, then, is what the current "rules" are for appropriate weight/height ratios? Or are such measurements now thrown out in favor of body fat percentage measurements? She's 5'1" and I'm 6'1" and we're curious what the medical rule of thumb would be for how much each of us "should" weigh...mostly because we're wondering if it takes into account things like muscle mass. What would the current medical/health industry recommend each of us weigh? Are these numbers accepted or are they seen as not as important as they might have been 20 years ago. If you have actual numbers, we'd be curious to see that too. Thanks! I have a dinner riding on this!

2) Could you clarify the Body Mass Index deal? According to one BMI chart, I am "slightly overweight" because I am 5' 5-1/2" tall and weigh 160 lb. I am also very muscular and have a large frame. The lower BMI readings are labeled "ideal," but I've heard muscle weighs more than fat, so if the chart does not include the muscle factor, is it basically saying that it's "ideal" NOT to have extra muscle? I look slender and have never been told by a doctor to lose weight. I'm a twenty-four-year-old female, lacto-ovo-vegetarian, and get lots of exercise, including walking and frequent "sweaty" workouts.

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?