Diets, nutrition and weight loss have been a long time interest of mine. I’m not sure why, as I have never been overweight, I’ve never had an eating disorder, and as far as I know, I’ve never been malnourished. I did adopt a vegetarian diet when I was twelve years old, and so I’ve spent the majority of my life defending a meatless diet to friends, family members and even doctors, which may have inspired me to learn more on the subject, but that doesn’t fully explain my fascination with diets and weight loss.
Before anyone gets concerned, I want to make it clear that my fascination with these things does not mean I put any of them into practice! I have never been on a weight loss diet, or any temporary fad diet. I did do a raw food cleanse for seven days last February, but the intention was to reset my palate, and see if my skin cleared up, not to lose weight. I am more interested in why I am not overweight, but so many people are, and what they can do to lose weight. My only interest in fad diets is how to debunk them so I can steer my friends away from them.
Most of my knowledge on the subject of weight loss comes from documentaries, online resources and podcasts. It’s all stuff I have pieced together over the last fifteen years. I try my best to be skeptical of things that don’t have a solid scientific background, or sound too good to be true, but I will admit I don’t always check sources. Even so, I think that most of the information I’ve compiled would be very useful to a person who wants to lose weight, or eat more healthily in general.
Weight gain or loss, at its simplest, is a budget. To maintain weight, you need to eat the same number of calories as you expend, to gain weight, eat more than you expend, and to lose weight, eat fewer. It does get a lot more complicated than that, but the details are for another day. Almost everyone who has ever tried to lose weight (and even those who have succeeded!) will tell you it’s not as easy as “eat less.” There are two sides to the weight loss equation, though, as with any budget: how much you eat, and how much you move.
So, what if you don’t want to eat less, and you just want to exercise more to lose weight? That could work, right? Sadly, the answer seems to be ‘no.’ I had heard this many times before, that it is nearly impossible to lose weight through exercise alone. I didn’t really think about how much more important diet is than activity level when it comes to weight loss (/maintenance/gain) until last week, when I looked at my runkeeper stats.
I’ve been using runkeeper since April of 2012, and in that time I have run almost 700 miles. That is over one hundred and thirty hours of running. That’s a lot of exercise. It got me thinking, if I didn’t eat more calories to compensate for all that running, how much weight would I have lost in that time? Runkeeper estimates my total calories burned from running at 72,158. At first, that number seems enormous. Certainly, if you ate that many calories in a day, or even in a week, you’d be sick. I didn’t do all of that running in a day or a week, though, it took me 499 days. Over 499 days, that’s only 144 calories per day. In other words, one pint of juice per day. Back to the original question, though, how many pounds of weight loss would that be, if I didn’t compensate by eating more? Assuming I only lost fat, and not muscle or other lean tissue, there are approximately 3,500 calories per pound of fat, so dividing the total calories by 3,500 I get 20.6 lbs. I was astounded at how low the number was. Almost 700 miles of running, and that equates to less than 20 lbs of fat?! How could that be? Running is hard work, and it takes a lot of time. It seems like surely it would help you lose weight.
The truth is, by simply having a glass of juice, or a cupcake, I can easily erase an entire run from the calorie budget. My longest runs are over 10 miles, and that ups the ante to around one thousand calories lost, but I can’t run 10 miles every day, or even more than once a week. Even if my body were conditioned to do that, I don’t have the time.
Our bodies have evolved to expend as little energy as possible, because food used to be scarce. Walking, running, or even doing burpees and climbing over obstacles requires very little extra energy from your muscles. Heavy weight lifting and sprinting use more calories, but are unsustainable over enough time to make a significant difference.
Sadly, if you are eating 700 extra calories per week (just one sugary soda a day), you would have to run seven miles every week to burn it off. If you’re overeating by 800 calories a day, you’d have to do a couple hours of vigorous exercise every day to not gain weight.
Don’t get me wrong, I’m not suggesting that exercise isn’t useful if you’re trying to lose weight. Some exercise helps in more ways than just straight up calorie burning. Exercise is shown to suppress appetite, making it easier to eat less, and if you are a person who eats when you’re bored, or when you’re sitting around, you are removing a snacking opportunity from your schedule. Also, data compiled by the National Weight Control Registry suggests that people who exercise daily are more successful in keeping weight off once they have already lost it. Exercise also has many other health benefits that diet alone cannot provide, and I think everyone should exercise regularly, just not as a standalone solution for weight loss.