Should I Eat on Bicycle Rides if I Want to Lose Weight?

Question: I took up cycling this year to lose some weight (okay, a lot of weight). I started with a mountain bike but soon discovered I loved being a roadie, so I switched over. As the pounds peeled off, I started riding farther. My goal is to do a century by the end of the summer. But when I ride as far as 60 miles, I get exhausted. Maybe I should I be snacking to increase overall exercise time, but does it make any sense to eat on the bike when I’m trying to lose weight? — Gus T.

RBR Replies: That’s a great question. It does seem logical that you shouldn’t eat during rides. After all, weight loss is based on increasing caloric expenditure coupled with consuming fewer calories. So why add some by munching as you ride?

As in many other areas, what seems logical ain’t necessarily so. Weight loss is a subject fraught with paradox. Here are three important reasons to eat while riding:

First, the more you ride, the more calories you burn.  But you can’t ride longer than about two hours before your stored glycogen (muscle fuel) is depleted. At that point, you feel tired and even miserable. But if you eat, you can ride much longer and burn substantially more calories even though you add some. Hence, the paradox: You have to eat in order to ride long enough to burn significant calories and lose weight.

Here’s a quick example. Let’s say you burn an average of 550 calories per hour on a ride. If you don’t eat, you can ride two hours before feeling fatigued and on the way to wretched. That’s 1,100 calories burned. But if you nibble an energy bar (225 calories) and drink a bottle of sports drink (125), those 350 calories enable you to complete a four-hour ride feeling pretty good. So your net loss for the ride is 1,850 calories. This represents just over half a pound of body fat.

Second, although duration is important, so is intensity.  And you can’t go fast unless your body has a lot of carbohydrate to burn. Bodies that exhaust their glycogen stores have to burn predominantly fat — and fat metabolism means you can’t ride hard. On the other hand, if you conserve muscle glycogen by eating carbs as you ride, you’ll be able to go at a higher calorie-incinerating pace.

Third, you don’t burn calories only while riding.  You burn them just by being alive. And fast riding is one of the best ways to keep your metabolic rate elevated after you get off the bike. That’s when you really lose weight. It happens best after long, vigorous rides, made possible by eating on the bike.

One more point: Be careful when you set weight-loss goals. It’s tempting to try for extremely low body fat percentages. We tend to think of elite riders when we envision the ideal cycling body. But people who excel as pro roadies are often lean and light to begin with. The fact is, elite cyclists have chosen their parents very well.

It’s unrealistic for a large-boned person who stores fat easily to achieve a pro cyclist’s silhouette. It won’t matter how much he or she rides and restricts calories. Instead, this rider will slow down, get exhausted and hate the bike.

Have realistic weight-loss goals. You’ll get leaner, faster and climb better — within your genetic potential.