According to the results of a small scale study, it seems that overweight people are more likely to get allergies and asthma.

Dr. Deborah Gentile found that blood tests of overweight and obese patients with seasonal allergies had triple the levels of inflammatory proteins as normal weight patients with allergies.

"We've actually seen a big increase in allergies and asthma over the past decade and it coincides with this rise in obesity," said Gentile, director of asthma research at Allegheny General's Division of Allergy, Asthma & Immunology. "If you lose weight, you're going to be decreasing the amount of inflammation in your body and that, in turn, could lessen your allergies or asthma."

Seems like a catch-22 to me. People who have asthma and (seasonal) allergies tend to avoid sport and outdoor activities. Apparently, that further exacerbates your asthma and allergy risks. What to do? Consult your allergist or medical practitioner on how best to control and manage your symptoms to allow you to continue to exercise and enjoy the outdoors.