If you're trying to lose weight, having a snack at this time of day could wreck your progress.

Snacking can be helpful for weight loss. That's because a snack can keep you from growing so hungry that you overeat at your next meal. A new study, however, shows that some times may be better for snacking than others.

Researchers looked at 123 older women who were overweight or obese. For a year, all the women watched their diet, and some exercised frequently. Nearly all of the women had at least one snack during the day. Those who had a snack in mid-morning lost about 7 percent of their weight. That's not bad. But women who only snacked at other times of the day lost about 11 percent of their weight! For a 160-pound woman, that would be a difference of 6 to 7 pounds!

If you're keeping an eye on your weight, the next time you reach for a snack no matter the time of day be sure that:

• It doesn't have too many calories. 100 calories is a reasonable limit.
• And it should offer good stuff that you need, like vitamins and fiber. Fresh fruit, baby carrots, and air-popped popcorn are good options.

I'm Dr. Cindy Haines of HealthDay TV, with the news that doctors are reading; health news that matters to you.