The holiday season is rapidly approaching, and it’s kicked off by the biggest and most decadent feast of all: Thanksgiving.
Most of us gobble up well over 2,000 calories in that one colossal meal—that’s more than the U.S. Department of Health suggests we eat in a full day.
And with relatives soon to invade, presents to buy and thanks to give, it becomes easy to lose track of our health. Studies show that even nutrition-conscious eaters and fitness gurus tend to let loose during the holidays.
With the help of Dr. David Brock, Ph.D., an exercise physiologist and Director of the
Physical Activity and Wellness Laboratory at the University of Vermont, we’ve compiled a few ways to help you limit and burn excess calories and, more importantly, get you back out there exercising.
VS: What’s the best way to work off a 3,000-calorie meal quickly?
DB: That’s a good question—and it seems to be a popular one every year. Unfortunately, there isn’t a great solution in terms of a quick fix. There’s a lot of research that suggests all sorts of reasons for the way people metabolize calories differently. But I’m of the opinion that if you were to consume, say, a 3,000-calorie meal, and that was above your metabolic rate for the day, you’d have to expend that extra caloric intake so you don’t gain weight.
VS: Can you really “walk it off?”
DB: Most people burn about 100 calories per mile walking, but there is some variance there. The lighter you are, the less work it takes, so maybe you burn 85 or 90 calories. The heavier you are, the more work it takes, so maybe it’s 110 or 120 calories per mile. From a caloric expenditure standpoint, let’s just say you were to over-consume 1,500 calories—you’d have to set that by about 15 miles of walking. It’s a considerable expenditure to compensate for.
VS: What about running or hiking? How are those different?
DB: If you were to run a mile, versus walking a mile, in the confines of that mile, you would burn a similar amount of calories. The difference is time—it takes you about 20 minutes to walk the mile, and let’s say about 8 or 9 minutes to run the mile. So from a time standpoint, you can burn more calories running, but the work performed is pretty much the same.
There are caveats to that, though. For example, if the work is very intense, heart rate, core temperature, ventilation and other physiological responses continue to be elevated even after the exercise stops, so you continue to have a higher metabolic rate. So the higher intensity activity is the gift that keeps on giving, in terms of caloric expenditure.
You are unlikely to experience this with at walking because it’s relatively low intensity for most people. However, you may experience a similar post-exercise caloric burn with hiking a steep grade, even if you’re walking at 3 mph. The work being performed and the relative effort it requires really drives this. So a person running a quick pace may burn a similar number of calories as a person hiking a steep grade at a slow pace.
VS: How long would that phenomenon go on for? Let’s say you ran for seven miles at an 8-minute-per-mile pace.
DB: Say this eight-minute-mile pace was 90 percent of your maximal capacity—say that was a very quick pace for you. And let’s say you’re 120 or 130 pounds. You’d probably burn 95 to 100 calories per mile during the activity of running seven miles. But because that was such an intense exercise for you, your core temperature, (which is normally 98.6 degrees for most people), might go as high as 103 or 104 at that intensity.
Plus, many physiological systems— stress hormones, ventilation, heart rate, lactic acid—are all considerably elevated as a response to intense exercise. After the exercise bout stops, all of these systems want to return to the baseline resting state. This takes time and causes an individual’s metabolic rate to be elevated for quite some time after the exercise stops. In the literature it’s called EPOC, or post-exercise oxygen consumption, and reflects the energy required to return these physiological systems back to rest.
In the end, the high intensity exercise bout of 90 percent of maximal capacity (in this case running 7 miles at a 8-minute-per- mile pace) would probably result in about 700 to 800 calories expended during the run, and maybe another 200 to 300 after the high intensity exercise stops, for a grand total of 900 to 1100 calories burned.
If the same person was to at walk 7 miles at 50 percent of their max capacity, they may only burn around 750 to 850 calories. This can add up over time, but beginners and even advanced athletes should be careful to not make every exercise bout super intense.
VS: Is there a danger in the mentality that you need to work something off immediately?
DB: You mean if someone who feels poorly about overindulging decides they’re going to go out and be a weekend warrior? Absolutely, this can be dangerous. You increase your risk for injury if you do something like that, particularly if you’re not accustomed to that level of activity.
Interestingly though, if the activity that you’re doing is abnormal to your routine (and abnormal is a relative term in this instance), it can compromise immune function, as well. If someone’s running 100 miles a week and they do something like run 50 miles on one Sunday, that might be relatively abnormal. If a person’s been sitting on the couch for the last six months and they decide they’re going to go out on the bike path and run six miles, that would be abnormal from a relative perspective.
This can produce immune dysfunction termed an “open window period” for the next several hours, days and possibly weeks. It can make people more susceptible to getting the flu or getting colds if they overshoot an exercise bout based on their regular routine. Some other things to watch out for after a relatively extreme exercise bout are dehydration, heat sickness and possibly hypoglycemia and rhabdomyolysis.
VS: Is there one particular type of exercise that would burn more calories than others?
DB: This question is often posed, not just to me, but to other exercise scientists. We tend to view things from a scientific angle: what will get you improved maximal oxygen uptake, higher lactate threshold, weight control, etc.? We can give you that answer, but when scientific expectations meet real life, the best activity for an individual is one he or she will stick with and one that works well with his or her interests and lifestyle. High intensity running might be the best for caloric expenditure, but if I hate running, I am unlikely to stick with it for very long, and therefore it does not produce the outcome I want. I always recommend people find an activity that they’ll continue to do. Find something that you really enjoy and try to have some social support.
There’s no need to feel that you should try to work off that extra 1,500 calories the same day, or even in the next couple of days. I always try to explain the dynamic aspect of the term ‘energy balance:’ it’s really small perturbations that are the healthiest approach. If you were to overeat one day, be cognizant of that and maybe restrict calories a little bit the next day and the following day. Throw some exercise in there. It all seems to work out from an energy balance perspective.
If you’re talking about burning calories, is it more effective to mix up different kinds of activities?
DB: “If you’re strictly looking at caloric expenditure—I want to burn the most calories—do the activity that you can do the most intensely, that is the most work, and for the longest duration. No real secret to that.
When I do exercise prescriptions for people, normally the questions I ask first are, ‘What do you enjoy doing?’ ‘What are you currently doing?’ and then I try to increase what they currently enjoy doing.
I think mixing it up can convey many physiological and psychological benefits. Also, if you switch exercise around like that, it kind of confuses the muscles to a point where you don’t necessarily become super efficient. So if I was to run every day for six months, I’d become very efficient at running, and I mean that from both a metabolic standpoint and also from a mechanical standpoint.
Believe it or not, when you do that seven mile run at month six, you’re actually burning fewer calories than you did at month one because you’ve become more fit and efficient with your caloric expenditure. Mixing it up is a great idea, particularly if you’re interested in losing weight.
It’s also a great idea to combine strength training and cardio. A lot of people do only one cardiovascular activity, like walking or biking or hiking or swimming, and they combine that activity with a diet. In those cases, they actually end up losing a lot of skeletal muscle tissue as well.
So yes, you lose body fat, but you also lose skeletal muscle tissue. And skeletal muscle tissue is the primary driver of your resting metabolic rate. Skeletal muscle tissue requires calories. If you start dieting, and the only exercise you do is cardiovascular activity, you’re going to be more susceptible to regaining that weight when you come off that diet because you’ve lost metabolically-active tissue in the process. So I always recommend that people combine whatever the cardiovascular activity they like to do with something like strength training or CrossFit or yoga so they can try to maintain some of that skeletal muscle tissue.”
Dr. David Brock is an associate professor in the Department of Exercise and Movement Science at the University of Vermont. He has a B.S. in human nutrition, M.S. in exercise science, and a Ph.D. in exercise physiology.