How Much Protein Should You Eat During Fat Loss?
Study review on high vs low protein intakes during energy restriction combined with resistance training
Today, I’m going to be covering a paper that came out of McMaster University back in 2016 from Stu Phillips (who is kind of a rockstar when it comes to exercise science research…. not that that means anything to most people 😂).
This was a very well done randomized trial that controlled for basically everything, but sought to investigate how differing levels of protein intake would impact body composition and performance during a pretty large calorie deficit when combined with intense exercise.
Protein is something you’ll hear me and many coaches always talk about as being crucial when it comes to body composition goals.
Outside of actually lifting weights, it’s probably the second most important factor for maintaining lean mass while you lose body fat. Which is quite important for most of us for both health and aesthetic reasons.
Through my years of coaching, it’s something that most everyday people really struggle with getting enough of.
So let’s see how much of an impact it can make within the context of weight loss!
Methods
This study had 40 participants made up of young men who qualified as overweight according to BMI and had not been exercising previously other than light activity. More baseline characteristics can be seen below.
They were randomized into one of two groups: high protein and low protein (low served as “control” in the actual paper).
The high protein diet would consume 2.4 grams per KG of body weight (1.09 g per pound of BW) and the low protein group would consume 1.2 grams per KG of body weight (0.54 g per pound of BW).
Carb intake was similar between groups. This was done because there was plenty of high intensity exercise in the intervention and carbs tend to aid high intensity performance more than fats do.
Fat was pretty low in the high protein group and much higher in the low protein group. This had to happen in order to match relative calorie intakes between groups with differing protein levels.
Below you can see these categories broken down into further detail.
After baseline, each group was put on a 40% calorie deficit from estimated maintenance for 4 weeks. So each group was in a matched estimated calorie deficit, with differing macronutrient breakdowns. All participants were given all of their meals and protein shakes as well.
One thing I will add is that this is a much larger deficit than I recommend. So I wouldn’t replicate this at home.
Lastly, exercise was super high and intense in this trial. Both groups did the same program consisting of 6 workouts per week. 2 full body lifting circuits, two HIIT sessions, one stationary bike session and one plyometric circuit.
You can see the exercise description below:
Non exercise activity was accounted for too, as all participants had a hip-worn pedometer and were instructed to get 10K steps per day with the average step count of 11,915 steps per day between the subjects.
Essentially, this was a 4 week crash diet with INTENSE exercise. With all else equated other than protein and fat intakes (which is not something I’d really ever recommend).
Let’s see how that panned out.
Results
The results were pretty cool. Within 4 weeks, both groups lost significant amounts of weight. An average body mass loss of 12.98 lbs in the high protein group and an average of 7.7lbs lost in the low protein group.
What was most interesting, was that the high protein group lost significantly more weight and body fat than the low protein group WHILE also gaining more lean mass than the low protein group.
This is what we would call body recomposition.
Here you’ll see that the high protein group gained 2.64 pounds of lean body mass compared the low protein group gaining zero.
Side note: lean body mass does not automatically mean muscle tissue. I highly doubt these folks gained 2.64lbs of muscle tissue during 4 week while in a caloric deficit. While I assume they did gain some based off of this, lean body mass is all body mass that is not fat mass. They may have retained more water. If their muscles did grow, they could probably also be storing more muscle glycogen (stored carbohydrates in muscle to use for energy) and water within their muscles. So yes, they most likely gained actual muscle tissue, but 2.64 lbs of lean muscle tissue gained in 4 weeks while being energy restricted, is very unlikely.
While the high protein also lost 2.42 lbs more of fat mass than the low protein group did.
The biggest takeaway was that this was in energy matched deficits that also controlled for exercise and activity. Lending itself to the idea of how crucial protein intake (as an indepedant variable) is for maintaining (or even gaining) lean mass while optimizing body fat loss during energy restriction.
The final point was that essentially all performance measures made significant improvements, but they did not differ between groups. So if anything, protein seemed to help body composition more than anything else here.
Takeaways
It’s no secret that protein is important. You probably hear about it all the time. I wanted to break this down to demonstrate how much of a role it can make in regards to optimizing fat loss. It’s often a struggle for a lot of folks to get enough, so this evidence can help bring to light how important it is.
If you’re focusing on getting the most out of your training and weight loss goals, then protein is a no brainer to focus on.
With that being said, in context, I don’t think it’s fair to expect similar results to this paper.
1. This was a HUGE calorie deficit — One that I would never really recommend. As the magnitude of your deficit increases, protein tends to become more even more important for sparing lean mass. So if you’re in a small deficit (say 5–10% lower than maintenance, your protein intakes won’t necessarily need to be as high).
2. This was an excessive amount of training — You do not need to train like this, it’s pretty unsustainable. But, if you’re aiming to optimize fat loss, resistance training and high intensity training does seem to outperform lower intensity cardio though. This is because resistance training especially helps preserve and even promote building muscle, while lower intensity cardio doesn’t really.
3. This was on untrained and overweight individuals — If you’re on the leaner side or even the more trained side, you really should not expect similar results to this. Two things that tend to make body recomposition more likely is being untrained and having a higher body fat. If you’re neither of these, let’s not get ahead of ourselves. Now, there is evidence that more trained individuals can still gain muscle mass and lose body fat at the same time, but just probably not to this extent and in this short of time. Also, the training interventions would probably need to be even more lifting focused and protein intakes could potentially even need to be higher (that paper had some cases of people eating over 3.2g grams of protein per KG of bodyweight compared to 2.4g in this current study).
One other factor to think about when it comes to the population sample was this was all done on younger men. So we can’t guarantee that the same results will pan out for women or even older folks. With that being said, higher protein intakes during energy restriction does seem to positively impact seemingly all populations.
4. Lastly, an intervention such as this is not sustainable — This did show compelling evidence that high protein is superior to low protein during weight loss, but put bluntly, this intervention was not sustainable. Especially for untrained people like in this study. So let’s use this as evidence that higher protein is important during fat loss, but not as a template for how to reach your goals. Especially if you want to maintain said goal.
For application, I would summarize this:
If entering a calorie deficit, make sure you’re eating enough protein.
I use the sliding scale of 0.7–1.2 grams per pound of body weight. If you’re higher in body fat % or in a smaller deficit, the lower range will probably be great (around 0.7 grams per pound of BW).
If you’re leaner or in a larger deficit, slide up the scale. This study demonstrated great results from around 1.1 grams per pound of bodyweight in the high protein group.
The easiest way to get protein up during energy restriction is from a protein shake or shakes — you can have multiple servings per day (whey is considered a top source for muscle preservation due to its high leucine content).
Secondly, prioritize resistance training over low intensity cardio if you want to optimize fat loss and keep lean mass (which most people tend to want).
If you have any questions, feel free to reach out or even suggest anything you’d want me to cover in the future!
Cheers,
Coach Dylan 🍻
References:
Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial
https://academic.oup.com/ajcn/article/103/3/738/4564609
2. Body Recomposition: Can Trained Individuals Build Muscle and Lose Fat at the Same Time?
https://journals.lww.com/nsca-scj/Fulltext/2020/10000/Body_Recomposition__Can_Trained_Individuals_Build.3.aspx