What are the real benefits of exercise?
I’ve noticed quite a few runners and bikers in the neighborhood this summer. I’ve also noticed an increase in the number of folks lined up at the local ice cream shop and wondered at the intersection of these two groups — the exercisers and the summer eaters. Conventional wisdom tells us that if we’re going to eat calorically dense foods, we need to be prepared to work off the potential extra pounds.
Before I go on, let’s take a little quiz. A little knowledge goes a long way in feeling good about your plans to exercise.
Unfortunately, the answer to question one is “d.” Exercise without dietary changes may not actually help many people to lose weight, no matter what the intensity or the duration (1). If it does help, it may only moderately reduce fat mass and weight for the majority of people. However, it may be helpful with weight maintenance. Therefore, it may be more important to think about what you are eating rather than succumb to the rationalization that you can eat with abandon and work it off later.
Don’t give up on exercise just yet, though. There is very good news: the answer to question two is that exercise has beneficial effects on all the choices plus many others, including diabetes, cardiovascular disease, osteoporosis, fatigue, insomnia, and depression. Let’s look at the evidence.
Weight loss attenuated
The well-known weight-loss paradigm in medicine is that when more calories are burned than consumed, we will tip the scale in favor of weight loss. The greater the negative balance with exercise, the greater the loss. However, the results of one study say otherwise. They show that in premenopausal women, there was neither weight nor fat loss from exercise (2). This was a preliminary study that involved 81 women over a short duration, twelve weeks. All the women were overweight to obese, although there was great variability in weight.
However, more than two-thirds of the women gained a mean of 1 kilogram, or 2.2 pounds, of fat mass by the end of the study. There were a few who gained 10 pounds of, predominantly, fat. There was significant variability seen among the participants, ranging from significant weight loss to substantial weight gain. These women were told to exercise at the American College of Sports Medicine’s optimal level of intensity (3). This is to walk 30 minutes on a treadmill three times a week at 70 percent VO2max —maximum oxygen consumption during exercise — or, in other words, a moderately intense pace.
The good news is that the women were in better aerobic shape by the end of the study and that women who lost weight at the four-week mark were more likely to continue to do so by the end of the study. Though this is an interesting finding about variable effects on weight with exercise, this was also a preliminary study, so there needs to be a larger and longer duration study to confirm these results.
Other studies have shown modest weight loss. For instance, in a meta-analysis of 14 randomized controlled trials — the gold standard of studies — results showed that there was a disappointing amount of weight loss with exercise alone (4). In six months, patients lost a mean of 1.6 kilograms, or 3.5 pounds, and at 12 months, participants lost 1.7 kilograms, or about 3.75 pounds.
However, exercise may be valuable in weight maintenance, according to observational studies. Premenopausal women who exercised at least 30 minutes a day were significantly less likely to regain lost weight (5). When exercise was added to diet, women were able to maintain 30 percent more weight loss than with diet alone after a year in a prospective study (6).
Chronic kidney disease
Chronic kidney disease affects about 1 in 10 people in the United States, according to the Centers for Disease Control and Prevention (7). The U.S. Preventive Services Task Force has indicated that there is insufficient evidence to treat asymptomatic CKD. In fact, the American College of Physicians has said that asymptomatic CKD, which includes stages 3a and 3b, or moderate disease levels, should not be screened for, since the risks outweigh the benefits and lead to false positive tests and unnecessary treatments (8).
However, in a recent trial, the results show that walking regularly could reduce the risk of kidney replacement therapy and death in patients who have moderate to severe CKD, stages 3-5 (9). Yes, this includes stage 3, which most likely is asymptomatic. There was a 21 percent reduction in the risk of kidney replacement therapy and a 33 percent reduction in the risk of death when walkers were compared to non-walkers.
Walking had such an impressive impact, results were based on a dose-response curve. In other words, the more frequently patients walked in the week, the better the probability of preventing complications. Those who walked between one and two times per week had 17 and 19 percent reductions in death and kidney replacement therapy, respectively, while those who walked at least seven times per week saw 44 and 59 percent reductions in death and kidney replacement. These are substantial results. The authors concluded that the effectiveness of walking on CKD was independent of kidney function, age or other diseases.
Unfortunately, more than three quarters of patients with rheumatoid arthritis are affected with varying degrees of hand dysfunction. Well, it turns out that a randomized controlled trial that included supervised (physiotherapist or occupational therapist) exercise for six sessions, and exercise at home showed more than twice the improvement in hand function than those in the usual care group, over a 12-month period (10). There were no changes in drug therapies or pain.
Therefore, while it is important to enjoy the remaining weeks of summer, which officially ends September 21st, it is food choices that will have the greatest impact on our weight and body composition. Exercise will not be the solution for most of us to overcome weight gain. However, exercise is extremely beneficial for preventing progression of chronic disorders, such as CKD. Improved functioning of the hand with exercise in rheumatoid arthritis patients reduces disability.
So, by all means, exercise, but also focus on more nutrient-dense foods. At the least, strike a balance, rather than eating purely calorically dense foods. They are unlikely to be rationalized with exercise.
(1) update.com. (2) J Strength Cond Res., Online, Oct. 28, 2014. (3) ACSM.org. (4) Am J Med. 2011;124(8):747. (5) Obesity (Silver Spring). 2010;18(1):167. (6) Int J Obes Relat Metab Disord. 1997;21(10):941. (7) cdc.gov. (8) Ann Intern Med., online, Oct. 21, 2013. (9) Clin J Am Soc Nephrol. 2014 July 9(7):1183-9. (10) Lancet., online, Oct. 9, 2014.
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com or consult your personal physician.