A trainer I have great respect for and have worked with a couple times once said to me that 80% of your body composition is determined by your diet. I’ve always found that a little bit confusing once you get down into the nitty gritty. Does that mean that you can lose 80% of the weight you need to lose? You can get in 80% better shape? Feel 80% better? There’s a study that outlines this pretty clearly where a diet intervention led patients to lose 8.5% and change of body fat and an exercise intervention led them to lose 2.4% or so. Diet plus exercise led to a 10.4% reduction. Certainly take a healthy grain of salt with this study because the patients in it had body fat percentages close to 50% when the intervention began, so I wouldn’t say it was an average swath of the population.
I think what the trainer was getting at was the fact that diet is hugely important when a person is trying to lose weight. In fact, most would say it is the most important factor. Matthew Walker would make a case that sleep is the best intervention because when we are sleep deprived, our bodies catabolize muscle rather than burning fat.
Either way, contrary to a decade or two ago, very few people are arguing that exercise alone or even embarking on a comprehensive plan to lose weight that focuses on exercise above all else has much chance for success. Our bodies are just too good at managing resources to hope that burning a couple hundred extra calories on the elliptical will lead to a caloric deficit over the long term. Either hunger will ramp up or expenditure will decrease (and likely both will happen) so that your body can hold onto the precious resources it has. Go check out the starting line of the next road race in your town, and you’ll see what I mean. These are “in shape” people who are carrying a lot of extra body fat around even though they are running 5, 10, 20, or 40 miles a week.
I was listening to a clip of an interview Joe Rogan did with Dr. Peter Attia (who is a flipping genius, by the way), and he had really interesting things to say about weight loss. The big takeaway was that fat loss is essentially figuring out the equation to get more energy out of your fat cells than is going in. That is a hormonal process in your body with a million variables. Limiting insulin via carbohydrate restriction was a big part of finding some success, but variables like chronic stress, menopause and sex-hormone levels, lipoprotein lipase function, low sleep, etc., etc. all play into the equation.
I know in my life right now, I am (effortlessly) hovering around 14 or 15% body fat. I’d be psyched to lower that a few points, but with little kids and regular low-level stress, I’m not sure it’d be possible for me to move the needle very much. Depending on where you are, that can be a frustrating or liberating thought.
So what does this mean for your day to day life if you’re looking to trim some fat?
Eat better. The same trainer I mentioned at the beginning of this post has a weight loss pyramid that looks something like this one. That’s not a typo…without your nutrition in line, weight loss is pretty much impossible, so it’s worth saying twice. Don’t make it too complicated when you’re trying to make this change. Ditch sugar, seed oils, and grains. Once you’ve done that, wait a few weeks. You’ll lose a bunch of inflammation and a little fat. After that, dial in your sleep, maybe start meditating, and begin to think about the role you want exercise to play in your life. You’ll lose a little more fat.
Some of us (my shameless self included) like to work out for the aesthetics. This is personal preference, but I tend to like a strong, explosive looking body, so I hit the gym a couple times a week and sprint around like a dog is chasing me once every week or two. (I know I've put that picture in before, but I love it, so I'll add it again)
Others are only interested in the longevity benefits of working out, and, still others, have goals like running a 5k, completing an ironman, or getting up and down the stairs without needing a nap. Whatever your goals are (and hopefully that includes enjoying your family, making time to read or do a crossword, and hanging out with friends), make sure your workout plan fits them.
Exercise is great and important. I feel better, look better, eat better, and truly believe I am promoting health and longevity by working out. BUT. If your goal is fat loss, start with your diet and go from there.