Will fasting before exercise help burn more fat?

Yes, and no. Yes, fasting prior to exercise has been shown to increase percentage of fat utilisation by up to 20 per cent. However, if glycogen (stored carb) stores are depleted, the body must obtain energy from elsewhere. This lack of stored carbs may force the body to breakdown skeletal muscle for energy, especially during an intense workout. If performance enhancement is your goal, research shows no benefit of fat adaptation for endurance athletes. If weight loss is the goal, potentially eating away muscle mass will make it harder to lose weight and maintain weight overall.

If you drink 100 per cent juice, is it as good for you as a whole fruit or vegetable?

Yes, and no. On the plus side, juice may contain more nutrients than a single piece of produce. An 8-oz glass of orange juice has 100 mg of vitamin C; an orange has 75 mg. But juice offers almost none of the fibre found in produce, and it packs calories. An 8-oz glass of orange juice has 120 calories and 0 g of fibre; an orange has only 60 calories and 3 g of fibre. The bottom line: Make sure that you mostly eat whole produce.

Can you get too much fibre? Adding up my fibre from all sources, I get 40 g a day.

It depends. We recommend 20 to 35 g daily – an optimum amount to prevent constipation, heart disease, and possibly cancer. Getting more fibre than that means that you absorb less of important minerals such as zinc, iron, and calcium. If you're getting extra fibre from eating lots of vegetables, beans, whole grains, and fruit, you probably get enough extra minerals to compensate. But if you're taking a fibre supplement, it could be leaving you short on some minerals.

I always take my vitamin with my morning tea. But now I hear that tea can keep some vitamins from being absorbed. Is that true?

Compounds in tea called tannins interfere with absorption of the mineral iron. If your doctor has told you you're low on iron, it's best not to drink your tea within 90 minutes of taking a multivitamin with iron or any iron supplements that have been prescribed for you. But don't ditch your tea: It's a powerful stew of antioxidants that may fight cancer and protect your heart.