"As American women age many begin a war with their weight. A new study shows for normal weight middle-aged women and older who eat a regular diet, 60 minutes of daily exercise is recommended just to maintain and not gain weight as they age. For overweight or obese women exercising 60 minutes wasn't enough to maintain weight over time."
-Dr. I-Min Lee, Division of Preventive Medicine Medicine and Aging, Brigham and Women's Hospital, Harvard Medical School, "Physical Activity and Weight Gain Prevention," JAMA March 24/31, 2010, 303(12):1173-79
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This article appeared in JAMA while I was in the North Carolina mountains for a week, helping my sister-in-law prepare for--and then celebrate my niece's wedding.
The only exercise I did for 6 days in NC was stuffing guest bags with homemade butter cookies, M & M trail mix, and chocolate covered pretzel sticks, in between eating the homemade butter cookies and M & M trail mix. And that doesn't count the caramelized onion heirloom mashed potatoes, creamed winter spinach and rainbow chard with Parmesan, macaroni & cheese with white truffle oil, and the amazing caramel creme brulee wedding cake served at the reception. And yes, I did order the vegetarian meal.
Dancing non-stop for three hours at the wedding reception definitely wasn't enough to burn the calories of everything I ate over six days!
When I got on the scale yesterday I had gained 3 pounds!
I'm here to tell you that Dr. Lee's research is right on the money--in my humble experience. I don't diet, but I do exercise in that over 21 MET/week range--and I haven't lost a pound in twenty years! But neither have I gained any weight in twenty years.
Can Exercise Prevent Middle Age Weight Gain?
Dr. Lee's research group had a brilliant idea. They knew that being overweight was a huge health risk factor. And they also knew that most diet & weight loss efforts don't last for long. First you lose, and then you gain it all back.
"We thought, wouldn't it be better to prevent the weight gain in the first place so you don't have to worry about sustaining the weight loss after that?" Lee said.
To that end, these researchers followed over 34,000 women, starting at around 54 years old, and followed them for 13 years. All the women ate their normal diet, recorded their weekly physical activity, and weighed in every three years. The women were divided into three groups based on how much they exercised:
- The most dedicated exercisers: 420 minutes a week or 60 minutes a day of moderate intensity exercise, like brisk walking; or an equivalent, like 30 minutes a day if they were jogging or running. This translates into 21 or more METS/week.
- The average exercisers: 150-420 minutes a week or about 20-60 minutes a day of moderate intensity exercise. This translates into 7.5 to less than 21 METS/week.
- The low volume exercisers: less than 150 minutes a week of moderate intensity exercise. This translates into less than 7.5 METS/week.
*Note: The study actually measured METS (metabolic equivalents) rather than minutes to create a level "playing field".
Here's how that works out: The 60 minutes/day group exercised for 21 METS/week. If you're a walker, that would be the equivalent of a 3 mph pace (a 20 minute mile) for 60 minutes a day which equals 3 METS. If you exercise more vigorously, like jogging at a 12 minute mile pace, you could reach 21 METS in just 2 1/2 hours.
Bottom Line: Only the women who started out with a normal weight (a BMI lower than 25), and exercised in the hard core range of 60 minutes a day (420 minutes a week) were able to either maintain their weight or gain less than 5 pounds over the 13 years--only 4,540 women or 13.3% of the study participants. The women with BMIs over 25 continued to gain weight even if they exercised for 60 minutes a day. To keep weight off as you age--get into the exercise habit early--and keep the BMI below 25!
National Exercise Guidelines Will Get You Healthy--But Don't Expect to Lose Weight!
The Federal government, the American College of Sports Medicine, and the American Heart Association have all advised us to exercise at moderate intensity for a minimum of 150 minutes a week to obtain "substantial health benefits". According to this study--that's just not enough, if you also want to prevent weight gain.
The Institute of Medicine has recommend that we need 420 minutes of moderate exercise a week (almost 3 times what the U.S./ACSM/AHA recommends) if we don't want to become overweight. According to this study--that's still not enough, unless you are already at an ideal weight.
The depressing news for all of us who exercise is that we need to kick it up a notch. Increase the exercise intensity & decrease the calorie intake.
"As people age it's clearly harder to keep the same weight so you have the option of exercising every day for an hour, really understanding that calorie restriction [might] need to be a huge part of your lifestyle because your natural tendency is to gain weight," according to Dr. Suzanne Steinbaum, Director of Women and Heart Disease at Lenox Hill Hospital in New York City.
There's No Escape From Exercise If You Want Good Health
Dr. Lee stressed that you shouldn't become discouraged if you can't reach the 60 minutes a day of exercise goal.
"It's very clear that even the lower levels of physical activity reduce the risk of important chronic diseases, including cardiovascular disease and certain types of cancer. There are still some health benefits."
Bottom Line: OK exercise might not keep you from gaining weight if you're taking in more calories than you can burn--but the benefits of exercise are tremendous. Exercise will decrease your risk of heart disease, type 2 diabetes, stroke, dementia, and some cancers. It will also lower your risk of anxiety and depression. Read "How Exactly Does Exercise Make Us Healthy? The Scientific American Asks the Experts" Click here
As Dr. Tim Church reminds us: "But to me, the most important element of exercise is healthy aging. There's no pill that assures that you'll be able to play with your grandkids or go duck hunting when you want to go duck hunting or get up and down stairs safely.
And there is one strategy which we know, which works great for aging, and that is being physically active and maintaining physical activity throughout a lifetime."
Why We Gain Weight As We Age
The JAMA article reminded me of an NPR interview I heard a month ago with Dr. Cheryl Phillips, president of the American Geriatrics Society, Dr. Jonathan Wanagat, a UCLA researcher, and Dr. Gail Greendale, UCLA geriatrician and researcher.
Dr. Cheryl Phillips:
- "There are some particular biological changes that happen as we age. For one, aging muscles actually contribute to the increase in the amount of fat we store in our bodies."
- "So, if you look at a woman who is 70 years old and compare her to what her body was like at 25 years of age, even though her weight may be exactly the same, she had more percentage of muscle in her body when she was 25 than she does when she's 70."
Dr. Jonathan Wanagat:
- We lose muscle cells as we age, and as older muscles cells get damaged they just don't get repaired as quickly as when we were younger. We don't know exactly why older muscles start shrinking--but they do.
- When older muscle cells aren't repaired, Wanagat says "they sort of whittle away and die." We can blame the loss of muscle fiber & the lack of muscle cell repair on decreases in growth hormone, testosterone, and estrogen.
Dr. Cheryl Phillips:
- "If you think of muscles as being the energy powerhouse of our body, that's where most of our calories are burned. And when we talk about metabolism, what we're really talking about is how efficiently those powerhouse cells--the muscle cells of our body--burn the energy we bring in.
- "If you keep your caloric intake exactly the same as you get older, those unburned calories end up as fat."
Dr. Gail Greendale:
- Exercise is the antidote for weight gain and muscle atrophy!
- "Countless studies have shown that exercise--even in people in their 80's--works. It actually helps the muscle cells get bigger and stronger."
Dr. Jonathan Wanagat:
- "We aren't sure exactly how exercise makes muscles stronger--but weightlifting at any age offers low risk and great benefit."
- "We know that exercise actually helps the muscle cells become bigger--and stronger."
Dr. Gail Greendale:
- "As we age the immune system can get out of whack, turning on an inflammatory response when there are no bacteria or viruses to kill, or keeping it on long after the body's invaders have left. Such inappropriate inflammatory response can actually damage one's own cells in whatever part of the body the inflammation occurs, whether it's in muscles, joints, or organs."
- According to Greendale, strengthening muscles through exercise can help prevent this type of inflammatory cellular damage, as well as the inevitable arthritis that often occurs with aging.
- Exercise, and muscle strengthening also helps our joints to tolerate the stresses and strains of movement.
- Greendale is currently working on a study to figure out which yoga poses are best for the aging body. "What are the muscles and joint forces generated by each yoga pose, and will these muscle and joint forces be strong enough to be a training stimulus--that is to say, make people stronger?" Stay tuned! I'll definitely be interested in the results of this study.
Last week I happened to listen again to an NPR Your Health podcast from August 24, 2009, "Interval Training for the Middle-Aged and Slightly Plump". I think this just might be the perfect tool for our middle-age tool box.
Here's the pitch:
Steve Boutcher, a professor of exercise science at the University of New South Wales, has research showing that interval training might be exactly what the middle-aged body needs to lose weight.
Professor Boutcher has documented the health and weight loss benefits of performing 20-minute interval workouts on stationary bikes 3 times a week. He had his participants alternate between 12 seconds of slow, gentle pedaling, and 8 seconds of intense sprints, pedaling as hard as they can. To read his article published in The American Journal of Physiology, click here.
"The 8 second sprint is doable by all the groups we've looked at--old people, and overweight people. Everybody, so far, we've tested has been able to do it. And in the 20-minute bout, the actual heart exercise is only eight minutes. So it's not actually that much exercise."
"Over the course of four months, participants lost an average of 6 pounds of body fat. By comparison, those who cycled at a steady pace for 40 minutes, without mixing in the interval sprints, lost less than 2 pounds."
And it gets even better. Participants improved both blood pressure and blood sugar readings.
What's Going On? It's the Catecholamines.
According to Boutcher our bodies produce higher levels of a chemical compound called catecholamines during sprint-type intervals that raise our heart rate.
"These are hormones that tell the fat cells to release their fat," according to Boucher.
But you don't need cycle to get that catecholamine-effect. According to Dr. Tim Church of the Pennington Biomedical Research Center, it's all about the interval--not which sport you pick. Try fast walking--just throw in some hills and pick up the pace--at intervals, of course.
The goal is to get your heart rate up to about 85% of maximum for short intervals, and then slow your pace back down to slow or moderate. Church says it's a very efficient way to increase fitness quickly. That's exactly the routine we follow in my spinning classes.So, there you have it. Now we have even more "must do" activities to fill our days. Add sixty minutes a day of exercise--unless we decide to pick up the pace and start running (don't think so!)--or switch to interval training. And don't forget about strength training, to maximize the caloric burn--gotta keep our body's "energy powerhouses" properly stoked if we want to burn up the inevitable goodies that will eventually come our way, like wedding cake.