What it means when food is said to have 'health halos'

Q: I've heard some that some foods have "health halos." What does that mean?

A: A food said to have a "health halo" is a food that sounds healthful or has one nutritious quality so it seems healthful in all ways, including being low in calories, when many times it is not. Sometimes a food gets a "health halo" just by being associated with a restaurant, brand or celebrity that we think of as a source of healthful food.

Some foods with "health halos" may have a healthy-sounding claim on the package such as natural, low fat or fat-free. But those terms don't necessarily mean the food is low in sugar or calories, or that it has any health benefits. Even if foods contain some healthful ingredients, it can be easy to overlook those foods' high calorie contents. Cookies made with whole-grain flour, muffins that contain grated carrots or fruit, and snack bars that include dried fruit and nuts all contain ingredients with health value, but they also typically contain large amounts of fat, sugars or both that increase calories.

Create eating habits that support a healthy weight and overall good health by making foods rich in nutrients and relatively low in calories - vegetables, fruits, whole grains and beans - the centerpiece of each meal and snack. Don't let label claims distract you from checking nutrient and calorie content on foods' Nutrition Facts panel, including the portion size that those figures represent. Complete your eat smart strategy with a mindset in which you base the amount you eat on physical hunger, rather than misleading cues like how "healthful" the food is or seems to be.

Q: I've heard that it's important to have proper fuel and liquids before exercise. How do I get enough for good exercise without getting too many calories?

A: You're right, food and fluid are important to get more out of your exercise and to feel better during and after. What and how much you need depend on how long and intense your activity is and whether you want to gain, maintain or lose weight. The key is to give your body what is right for you.

Water is the ideal beverage for most people. Drink enough before (and during) exercise to prevent dehydration, and then after to replace fluid lost in sweat. Most recreational athletes do well using thirst as a guide for how much to drink. For those exercising more than an hour or at high intensity, sports drinks supply carbohydrates for energy that's easily digested during exercise, along with the electrolytes sodium and potassium.

You likely don't need extra snacks for moderate activity of less than 60 minutes. If you exercise several hours after a meal and run out of energy without a snack, choose something that's appropriate for your level of exercise. A piece of fruit might be all you need. Or you may do better with small amounts of carbohydrate plus a little protein; perhaps combining a couple of choices such as yogurt, cottage cheese, a small bowl of cereal, a handful of nuts or a piece of fruit.

But if your goal is to avoid weight gain, or even gradually lose weight, that can easily be sidetracked by snacks or drinks before or after exercise that supply more calories than you burn. Most people, for example, burn 100 to 200 calories in 30 minutes of brisk walking.

If you have diabetes and your medications put you at risk of hypoglycemia, you need to know when you need extra carbohydrates before exercise. Talk with your health care provider or diabetes educators about what's right for you. However, many of today's diabetes medications don't pose that risk, so pre-fueling with extra carbohydrates can be counter-productive.

• The American Institute for Cancer Research (AICR) is the cancer charity that fosters research on the relationship of nutrition, physical activity and weight management to cancer risk, interprets the scientific literature and education the public about the results.