Does More Exercise = More Weight Loss?
Study review on differing amounts of exercise and subsequent weight loss
Some happy looking folks given’er on the airdyne bike
Today I’m covering a paper on differing levels of exercise dosage and changes in weight loss.
This is something I do every Friday on our five-elements newsletter. You can sign up here for free on our home page!
The goal of this is breakdown one research paper (exercise science/nutrition related) with a little more nuance than you may see in my average article or in a lot of the headline grabbing content you may see.
One thing to remember is that no single paper is the gospel or the final word. Bodies of research are always growing and the entirety of the body is more important than any single study.
We also always need to factor in the context of any given study. The methods, the limitations, the population. All of it. This is why no single study holds the entirety of truth around a given topic.
Science evolves with time. Which means we should never be too attached to any single outcome! The point of this is just help you become a little more evidence informed when it comes to understanding fitness and how you can apply some research findings into your own fitness journey.
With that out of the way, let’s get to it.
Methods
This study was done on a population of cisgender women who were sedentary, did not exercise, were overweight-obese based on BMI and were postmenopausal.
There were 4 groups in this study.
1. Control — kept everything the same
2. 4KKW — exercised enough to burn 4 calories per KG of bodyweight per week — this was half of the dose the NIH recommends for this population
3. 8KKW — exercised enough to burn 8 calories per KG of bodyweight per week — this was the dose the NIH recommends for this population
4. 12KKW — exercised enough to burn 12 calories per KG of bodyweight per week — this was 50% more than the dose the NIH recommends for this population
This exercise intervention took place over 6 months.
The researchers also took baseline step data and nutritional intake forms. They were instructed repeatedly that this was NOT a weight loss study and were told to keep their diets the same as before.
Finally, it is important to note that the exercise intervention was all cardiovascular work on either treadmills or recumbent bikes. So yes, these folks were not lifting (sad, I know).
Also, as mentioned above, this was not a dietary intervention study. This was assessing weight changes in an exercise alone intervention.
Findings
All exercise groups lost a *significant* amount of weight during the trial.
In research, significant does not mean “a lot”. Rather, it means that the findings are statistically significant. This means the outcomes were very unlikely just a product of sampling error or random chance. I mention this because below you’ll see they did not lose very much weight at all. But when running the data, the findings were statistically significant.
What was interesting, is that there was not a statistically significant amount of weight lost between groups. Even though they all exercised at much different doses.
The 4KKW group exercised 1/3 the amount that the 12KKW group did, yet the average weight loss for the 4KKW group was 1.4KG compared to 1.5KG for the 12KKW group.
Interestingly enough, the 8KKW group lost the highest average of 2.1kg, even though that is not statically significant compared to the other groups (meaning, it could very well be from random error/chance)
Above you’ll see the predicted weight loss (in grey) compared to the actual weight lost (in gold) between groups. You’ll see that the 12KKW group came short with the actual outcome. Yet, the 8 and 4KKW groups both outperformed the predicted weight loss.
Here we can see percentages of predictions vs outcomes. The 4KKW got the most bang for their buck with 136% of what was expected. 8KKW had 112% of what was expected and the 12KKW group only had 53.5% of what was expected.
Now one thing to note, the study did not list this data, but I would assume the higher dosage groups would probably have higher cardio improvements.
Weight loss ain’t everything and we cannot undervalue how important cardiovascular fitness is. So just because weight loss didn’t have the best ROI from higher exercise dosages, doesn’t mean other benefits won’t come from more exercise.
Interpretation
The researchers referred to the term of “weight compensation” when folks didn’t lose the weight they predicted. There was more compensation with higher dosages on average.
So one interpretation is that more exercise may also lead to more weight compensation if other interventions are not also applied.
Again, subjects were instructed keep their normal diets as opposed to also change their diets to aid more weight loss. Making this an exercise alone intervention for weight loss.
There are two proposed mechanisms to how you may compensate from what I gather:
1. Your body may conserve energy in other ways if exercise output gets higher than average.
This means you may subconsciously move less throughout the rest of your day. We’ve all experienced this after a gruelling workout that leaves us horizontal for the rest of the day. You may have burned a lot of calories in the session, but the fatigue after may have you move much less after and perhaps have your net energy expenditure around the same as when you don’t exercise.
2. You may eat more as a compensation.
We all probably know this too. The feeling of just being ravenous after excessive training. The 12KKW group may have burned 3x as much calories from exercise per week as the 4KKW group from their sessions, but it ain’t hard to eat that back if your hunger skyrockets. Which could reduce your overall energy deficit and subsequent weight loss.
Finally, this study population is pretty specific, so you can’t say for sure the same would happen in say, younger resistance trained men, but energy compensation has been documented in newer research.
One showing that around 72% of calories burned in exercise actually adds to extra calories burned throughout the day. So a 28% energy compensation and that was in a much larger and more diverse population.
Takeaways
-More exercise is not inherently better for weight loss
-Higher exercise dosages may in fact increase weight compensation and reduce expected weight loss- especially if you’re going from being untrained to training a lot.
-The sweet spot is an amount of exercise that is challenging and helps you make progress BUT doesn’t have you so fatigued your daily activity plummets while your appetite skyrockets
-If you’re aiming to lose weight, diet is the cornerstone and exercise is an aid. A fantastic aid at that, but it probably shouldn’t be the backbone of a weight loss goal. Diet and lifestyle habits should most likely be the top priority.
-Finally, weight loss is NOT everything. Exercise, regardless of weight loss is still FANTASTIC for you!
As always, if you found this helpful, I’d love your feedback. Or even forward it to a friend who might find it useful! It also helps me grow my audience and the amount of people I can help :)
Cheers 🍻
Coach Dylan