Exercise vs. Diet: Which Is More Important for Weight Loss?

It’s a no-brainer that diet and exercise are both crucial to your well-being and your waistline. And that generally adhering to recommended guidelines (like getting regular doses of aerobic activity and resistance training, filling half your plate with fruits and vegetables, and eating lean protein) is the best way to optimize your health overall. But what if you want to achieve something specific—to drop a dress size, say, or stave off heart disease? Research shows that, in certain cases, focusing on one over the other will give you better, faster results.

To give you a sense of the importance of practicality, consider this recent meta-study (i.e. a study of studies), published in the Journal of the American Medical Association, which sought to figure out “which diet works best?” by looking at the results of 59 individual studies. These studies included various nutritional recommendations, such as low-fat, low-carb, and so on. Which of these recommendations reigned king? None. There were no major differences between the diets, and success was completely dependent on what the individual could adhere to. In other words, practicality reigned king.

Similarly, one of the most frequent questions that’s asked by aspiring fitness enthusiasts is “Which is more important: diet or exercise?” With practicality in mind, we decided to take a look at the evidence.

A Primer on Calories

It’s clear that you need to restrict calories in your diet to lose weight. Most people who exercise to lose weight and don’t restrict calories shed only 2 to 3 percent of their weight over 6 to 12 months. The reason? It’s much easier to deny yourself 500 calories a day—the amount you typically need to cut to lose a pound a week—than to burn that much through exercise. For instance, to work off almost 500 calories, a 155-pound woman would have to spend an hour pedaling a stationary bike at moderate intensity. Compare that with swapping a Starbucks Grande Caffé Mocha with 2 percent milk (200 calories without whipped cream) for a plain brewed coffee (5 calories) and eliminating a nightly bowl of ice cream (about 200 calories in a half cup) and a handful of potato chips (almost 160 calories). A bonus benefit of losing weight: Shedding about 5 percent of your body weight will reduce your risk of developing diabetes by almost 60 percent.

Take action: Eating fewer calories is pretty straightforward when you follow three guiding principles. First, stick with a primarily plant-based diet (fruits, vegetables, whole grains, beans, nuts, and heart-healthy fats, like olive oil). Second, limit processed foods (such as frozen meals, deli meats, and refined carbohydrates, including pastries and white bread), which contain lots of empty calories in the form of sugar and unhealthy fats (not to mention a lot of salt).

If you follow these two guidelines, you’ll automatically be doing a third thing that is linked to reduced calorie intake: eating more low-calorie–dense foods. High-calorie–dense foods (like full-fat cheese and red meat) pack more calories ounce for ounce than low-calorie–dense ones (like vegetables, fresh fruits, and whole-grain cereal). According to a study published in the journal Appetite, eating a low-calorie–dense diet (by decreasing fat, eating more produce, or adding water to recipes) helped people consume 230 to 396 fewer calories a day.

What the Research Says

Dr. John Briffa, who runs an excellent health blog, analyzed a study examining weight loss without dietary intervention here. He explains:

In this study, 320 post-menopausal women whose weight ranged from normal to obese were randomised to either an additional exercise or no additional exercise group (the control group). Those in the exercise group were instructed to take 45 minutes worth of moderate-vigorous aerobic exercise, 5 times a week for a year. Both groups (the additional exercise and the control group) were instructed not to change their diets.

At the end of the year, it was found that the exercise group, compared to the control group, lost an average of 2 kg (4.4 lbs) of fat. I’d say that quite a lot of us would be glad to drop a couple of kgs of fat. But now I’d also like to focus on what these women had to do to achieve this loss.

While the exercise group were instructed to exercise 5 times a week for 45 minutes, what they actually did was exercise for an average of 3.6 days each week. Total exercise time averaged 178.5 mins per week. We can multiply this by 52 to get the total number of minutes exercise over the course of the year, and divide this by 60 to convert it into hours. Doing this, we get a total of just under 155 hours. That’s about 77 hours of exercise for each kg of fat lost.
Most people would balk at the idea of exercising for 77 hours to lose 1 kg of fat. (Or equivalently 35 hours to lose 1 pound, for us American folk.)


But what about simultaneously exercising and accounting for dietary intake?

One study, published in the International Journal of Obesity and Related Metabolic Disorders, took trained subjects and had them track dietary intake along with energy expenditure. On paper, there was an overall caloric deficit created by the subjects. However, when researchers examined empirical changes, no weight was actually lost. As it turns out, subjects were simultaneously underestimating caloric intake and overestimating caloric expenditure.

Compare the studies above to the hilarious self-experiment by a nutritionist who went on the “Twinkie Diet” and subsequently lost 27 pound in 10 weeks. (Pro tip: Don’t try this at home.)

Why Exercise-Focused Regimens are Relatively Ineffective for Weight Loss

If you’re astonished by the details above, do not fret. There’s a simple description behind it, which we’ll break up into 2 parts

Reason 1. Calorie expenditure through workout is reasonably little in the grand scheme of traits.

In order to see why exercise-focused weight-loss programs may yield low effectiveness, it is essential to understand the accounting behind our day-to-day calorie expense.

We spend most of our calories every day simply “staying alive.” This is known as our “resting metabolic rate.” The Katch-McArdle formula, which takes into consideration one’s body fat portion, is the most precise method to determine this number, which is equivalent to:

9.81 x your amount of non-fat mass + 370 calories per day

Let’s say you are a 200 pound man who is at 30% body fat. You expend 1,743 calories each day just staying alive. (200 x (1 -.30) * 9.81 + 370 calories).

He’ll expend about 10% on top of that by what’s called the Thermic Impact of Food (TEF): the quantity of calories that he invests digesting and absorbing his dietary consumption.

Add another 10% on top of that through a metabolic procedure referred to as NEAT (Non Workout Adaptive Thermogenesis). This is the quantity of calories wasted through things such as fidgeting. Unfortunately, this can vary significantly from individual to specific.

This means that without even getting out of bed, our subject has currently expended 2,100 calories.

Now, add another 10% for getting out of bed and tackling his everyday routine and he’s currently burned 2,300 calories.

Adding exercise into the equation hardly makes a dent in his total caloric expense; the majority of the work is done before he places on his running shoes. Now I am not saying that you should not exercise, however rather, it is necessary to realize where a majority of your caloric expenditure is coming from. You would not use up a paper path in order to enhance a 100k/year wage, would you?

Reason 2. People are awful estimators of calories in vs. calories out.

Take a look at another research study, this one in the Journal of Sports Medication and Physical Physical fitness, in which scientists asked the topics to exercise, approximate their calorie expense, then took them to a buffet later on. Subjects were asked to consume the quantity of food that they believed they burned in calories. (Sidenote: Where can I register for one of these?).

The subjects ended up eating 2-3 times the amount of calories that they burned.

The takeaway from all this info is that calorie expenditure does not count for much, and people are normally terrible at estimating both expenditure and intake.

How to Effectively Incorporate Diet and Exercise

To make more sense of incorporating diet with exercise, I turned to my friend and obesity expert, Dr. Yoni Freedhoff. Yoni runs one of the largest obesity clinics in Canada and has helped countless individuals lose weight with a health and fitness approach. Yoni explains:

Most people I see struggle far more with their kitchens than with their gyms. They’ll readily find 30 minutes or more a day to hit the gym, go for walks, or simply up their daily activity by parking further away and taking the stairs more often, than they will for packing a lunch, prepping ingredients, cooking dinner, or keeping a food diary. I think in part it’s because that’s what the world believes — fuelled no doubt by shows like The Biggest Loser, and by the huge amount of money the food industry is throwing at the message of ‘balancing’ energy-in with energy-out, but also because we don’t get endorphin rushes from chopping vegetables or washing tupperware.

He then goes on to elaborate.

Most folks want to lose weight and to improve health and so both gyms and kitchens are required. That said, if weight’s a primary concern, I’d never ditch the kitchen in order to find the time to exercise. Instead take the total amount of time you think you’re willing to spend in the gym, and formally dedicate at least a third of that to the kitchen. As far as optimal amounts go, a person needs to like the life they’re living if they’re going to sustain it, so what’s right and optimal for one person will be too little or too much for another. The simplest litmus test question to ask is, “could I live like this forever,” and if the answer is “no,” you’ll need to change something up.
Given that Yoni has worked with a tremendous amount of successful patients, I asked for their commonalities.

The people who are most successful are those who embrace both consistency and imperfection. Think of starting out a weight management or healthy living program like you would a martial art. You’d never expect yourself to have a black belt from the get go. Instead, you’d start with really basic moves that you’d practice over and over and over again, you’d fall down a bunch, and doing so would be an expectation, and not a disappointment. And then slowly but surely you’d get better and better at it. Same thing is true when building any skill set, including healthful living, and just like you might be able to picture a jumping spinning hook kick in your mind’s eye when you start out at your dojo, that doesn’t mean you’ll be able to simply do one. So, too, with healthy living. Sure you might have a mind’s eye idea of what your healthy lifestyle should look like when you’re done, but getting there will be slow, plodding, and will include many falls.

He also shares some more great tips.

Never eat lunch out unless someone else is buying. Doing less exercise consistently is better than doing more intermittently – there are virtually no studies on diet or exercise that are long enough in duration to translate into lifelong recommendations or conclusions. Spending 2-3 minutes a day with a food diary is likely to have a bigger impact on your weight than 30 minutes a day in the gym.

Where to Go From Here

OK, so I’ve offered you a great deal of details suggesting that workout, as the sole ways of developing weight loss, is relatively inefficient or even counterproductive. Here are the actions that you should take in order to ensure your success.

1. Figure out how lots of calories you use up every day. You can utilize ExRx’s calculator here. For best accuracy, determine this by body fat percentage.

2. Minimize your calorie intake by 20% of your maintenance calories. Whenever you reduce your caloric consumption, it’s handy to all at once increase your quantity of protein in order to remain satiated. (Protein likewise has the higher Thermic Impact of Food out of any macronutrient, suggesting your body needs to expend more energy to digest it in comparison to carbs or fats.).

Just how much protein should you be consuming on a calorie deficit? Nutritional expert Alan Aragon recommends figuring out your target body weight and getting that quantity in grams. For instance, if you are a 200 pound woman who desires to come down to 120 pounds, take in a minimum of 120 g of protein daily.

3. When you are comfortable with counting calories, consider switching to counting macronutrients instead. Concentrating on macronutrients, rather than calories calories, is a nice “hack” to interrupt the fact that individuals (myself consisted of) are often translating exercise and consuming into the same currency: calories.

You’ll notice that the weight loss suggestion above makes no mention of exercise. But while you shouldn’t be factoring exercise into your calorie expense or intake, you ought to still be integrating it as much as “possible” practical.

“Sure, weight is lost in the kitchen,” says Dr. Freedhoff. “But health is gained in the gyms.”