The single biggest marketing slogan for nutrition or fitness programs is “Lose Fat and Gain Muscle”.
Whether it is actually possible to do so has remained a topic of great debate over the last several decades. Recent studies in the past years have given us the data needed to draw a conclusion on whether it is indeed possible.
Before we dive into the studies and the data lets discuss the hypothesis and arguments surrounding the issue.
Regulating Body Mass
The main argument against the idea of losing fat and gaining muscle simultaneously is essentially the notion of calories in versus calories out.
The argument goes something like this: depending on your caloric balance your body is either in a net state of anabolism (building new tissue) or catabolism (breaking down tissue)
The calories in calories out (CICO) model holds a lot of truth and can explain a lot of the variation in body weight, yet it is incomplete.
I like to compare the CICO model with Newtonian Physics… it is accurate and describes gravity for a majority of cases but it is not complete. We need Einstein’s theories of relativity to describe the enormously large* and fast and we need quantum theory for the incredibly small.
I believe the CICO model breaks down in certain situations.
One such area where it breaks down is for anabolism and catabolism to be occurring simultaneously in different “compartments” of the body.
The CICO model essentially treats the body as a bomb calorimeter and an isolated system immune to perturbations. This is inaccurate. The body is not simply a bomb calorimeter, nor is it an isolated system.
The body is dynamic and responds to both internal and external stimuli (Figure 1).
I want to take the internal stimuli first and relate it to the topic at hand (building muscle).
Without even touching nutrition we have data to show that the body has internal signals that simultaneously induce muscle protein synthesis and increase fat oxidation, namely the hormone testosterone. It is well documented that testosterone increases muscle protein synthesis and that it can do so without increased amino acid uptake into cells (1,2,3). Additionally testosterone can simultaneously increase lean mass and decrease fat mass in an older population (4).
Now onto external signals. It is clear that ingestion of protein elicits muscle protein synthesis in humans (5,6,7). Now there are good arguments for what type of protein/amino acids are the biggest inducers of muscle protein synthesis but that is superfluous to the point at hand. It is enough for this argument that as a nutrient, protein elicits an anabolic signal of muscle protein accretion in humans. This effect is robust and reproducible in various populations.
The next external signal that elicits a robust, repeatable signal for muscle protein synthesis is exercise, with resistance training showing the greatest amount of muscle protein synthesis(8,9,10). In addition to signaling muscle accretion, exercise can also induce a signal for lipolysis and fat oxidation.
So let’s stop and review. The CICO model only really accounts for total body mass and predicts overall changes in the mass of a system. The body is more than a bomb calorimeter, it is dynamic and responds to signals and can change the masses of different “compartments” in accordance with the signals.
We have two easily modifiable signals we can use to elicit our goal of increasing muscle mass: 1) consuming protein, 2) engaging in resistance exercise. We also have covered 1 signal for eliciting our goal of fat loss: exercise.**
This figure wraps up these ideas quite nicely (figure 2).
Dietary protein and exercise essentially can act as leverage points. So to take Archimedes favorite quote, “Give me a place to stand and with a lever I will move the whole world” and spin it … “Give me some protein and with a good resistance training program I will build muscle and lose fat simultaneously”.
So without getting too far into the weeds we have a mechanism by which the goal of “gaining muscle while losing fat” is, at least in theory, possible.
Now let’s look at two separate studies using two very different approaches to see how this translates into practice.
I am going to summarize the findings over the next few paragraphs but a full discussion of each will appear at the end of the article for the interested reader
The first study was a protein overfeeding study in which they had resistance-trained volunteers consume either a “normal” protein diet or an overfeed protein diet in which they were instructed to consumer more than 3g/kg of protein per day (see table below for macronutrient and calorie breakdown) (11). Briefly, the high protein group consumed about 500 calories more per day, with about 80 of those calories coming from carbohydrates (not statistically significant from the normal protein) and about 350 calories extra from protein (this was statistically different), and about 60 calories from fat (also not statistically different).
During the dietary intervention the participants continued to resistance train for 5days/week for 8 weeks.
At the conclusion of this study the high protein group lost an average of 1.6 kg of fat mass with the normal protein group only lost 0.3 kg. Additionally, the high protein group saw a 2.4% decrease in body fat with the normal protein group saw a 0.6% decrease in body fat.
This figure is recreated from data in the Antonio et al. 2015 JISSN paper.
Although the high protein group consumed 350 more kcals per day than the normal protein group, the high protein diet group saw no change in body weight (-0.1 kg) while the normal protein diet group saw an increase in body weight (1.3 kg). This is quite interesting in that the increase in total body weight suggests that the normal protein group was likely already in a hypercaloric state as they increased their body weight, yet the high protein group which consumed even more calories (about 20,000 kcals more over the whole study) did not see an increase in BW.
Where the first study was considered “protein overfeeding” and hypercaloric, the second study is presented in the context of eating higher protein in the context of caloric restriction***.
In this study the researchers recruited 40 overweight (BMI >25) young men (mean age 23 years old) for this single-blind, prospective trial. All the participants were recreationally active, but were not regularly performing resistance training (so this is a relatively untrained population compared to the study from the Antonio lab) (12)****.
The participants were randomly assigned to either a high protein (2.4 gkg/day) or control protein (1.2g/kg.day) diet that was energy restricted by approximately 40%. Please see Table 2 for a complete breakdown of the diets and the differences between them. Briefly, one was a high protein, low fat diet, while the other was a “normal protein”, “normal fat” diet.
This table is directly from the Longland et al. 2016 AJCN paper
The participants also began a 6 days/week exercise program for the duration of the study (4 weeks).
When we look at the results of the study, we see, as expected in a 40% calorie restricted diet, that both groups lost body weight with similar weight losses between groups.
This figure is directly from the Longland et al. 2016 AJCN paper
The Wrap Up
The CICO model only really accounts for total body mass and predicts overall changes in the mass of a system. The body is more than a bomb calorimeter, it is dynamic and responds to signals and can change the masses of different “compartments” in accordance with the signals.
By manipulating the signals going into the system through proper diet and exercise it is indeed possible to simultaneously increase lean mass while reducing fat mass. It appears that this phenomenon may be more robust in untrained individuals than trained individuals, yet based on the studies from the Antonio lab it appears possible in trained populations as well.
For the interested reader please continue to the work below for more in-depth analysis of the two studies.
In Depth Review of Study 1
73 resistance-trained subjects volunteered for the study. The authors unequally randomized the subjects to take into account the loss of subjects from potential lack of compliance due to the high protein diet, as was seen in their earlier study.
The Nutrition Intervention.
The control group was instructed to maintain the same dietary and training habits over the course of the study. The subjects in the high protein diet group were instructed to consume ≥ 3 grams of protein per kg per day (or ≥3g/kg/day).
Consuming ≥3 g/kg/day from whole foods is pretty difficult so the participants on the high protein diet were able to consume commercially available whey or beef protein powder.
The investigators used My Fitness Pal to track food intake so it was likely pretty spot on for this study.
Each participant was instructed to follow a resistance training program. It is fully described in the paper. Briefly, the program was 5 days/week for 8 weeks, and was a “split routine”.
Also, “The investigators and research assistants were in contact with each subject on a weekly basis to ensure compliance with the exercise training program. Compliance was determined via measurements of volume load (repetitions × sets × weight) which should have increased over the course of the treatment period. Furthermore, subjects were instructed to not perform any aerobic exercise during the treatment period”.
As with previous papers we have talked about they used one of the better methods of testing, Air Displacement Plethysmography, AKA BodPod.
The authors wanted to see if the high protein diet had any impact on performance so they did pre and post-tests of a 1 RM for bench press and squat, as well as vertical jump, broad jump, and total pull ups.
Basic Metabolic Panel
Since the idea that protein is bad for your kidneys, liver, bones, etc. they also conducted a basic metabolic panel to track changes over the high protein feeding study. They measured: Calcium, Carbon Dioxide, Chloride, Creatinine with GFR Estimated, Glucose, Potassium, Sodium, Urea Nitrogen (BUN) and BUN/Creatinine Ratio (calculated).
As with most human research there were several particpants who dropped out; 15 and 10 subjects in the high protein and normal protein groups respectively. This leaves us with a total sample size of 48
Let’s get this argument out of the way first so there is minimal internet quibbling. Here is the dietary intake of the groups.
As you can see the high protein group consumed about 500 calories more per day, with about 80 of those calories coming from carbohydrates (not statistically significant from the normal protein) and about 350 calories extra from protein (this was statistically different), and about 60 calories from fat (also not statistically different).
Overall, the high protein group ate more calories, with roughly 70% of those calories coming from protein.
Both groups saw decreases in body fat mass and body fat percentage and increases in fat free mass. The high protein group lost an average of 1.6 kg of fat mass with the normal protein group only lost 0.3 kg. Additionally, the high protein group saw a 2.4% decrease in body fat with the normal protein group saw a 0.6% decrease in body fat.
Although the high protein group consumed 350 more kcals per day than the normal protein group, the high protein diet group saw no change in body weight (-0.1 kg) while the normal protein diet group saw an increase in body weight (1.3 kg). This is quite interesting in that the normal protein group was likely already in a hypercaloric state as they increased their body weight, yet the high protein group which consumed even more calories (about 20,000 kcals more over the whole study) did not see an increase in BW.
The individuals in this study saw no changes to any of the metabolic measures. One thing I would like to have seen were lipid profiles and markers of oxidation, just for more data points.
This study also provides more data points for high protein diets not changing creatinine, which has been an argument against high protein diets in the past. You can now add this to several other studies showing the same thing (1).
The Wrap Up
This is the second study to show that consuming extra protein on top of normal calories has, what I would call, a beneficial effect on body composition when consumed in conjunction with resistance training.
In Depth Review of Study 2
40 overweight (BMI >25) young men (mean age 23 years old) were recruited for this single-blind, prospective trial. All the participants were recreationally active, but were not regularly performing resistance training (Please see table 1 for participant characteristics).
The participants were randomly assigned to either a high protein or control protein diet that was energy restricted by approximately 40%. Please see Table 2 for a complete breakdown of the diets and the differences between them. Briefly, one was a high protein, low fat diet, while the other was a “normal protein”, “normal fat” diet.
Now the diets themselves were rather interesting in this study. From my analysis of the methods it looks like they received 2 meals a day along with “nutritional beverages” to round out the calories and macronutrients.
Before the hounds descend and cry about whether the participants actually ate their diet, the researchers provided the participants with ALL meals and beverages (save water and non-caloric drinks). The researchers also had daily contact with the participants and based upon their analysis deemed dietary compliance to be around 93%.
All exercise was completed within the controlled environment of the laboratory 6 days a week. The training consisted of the following:
- 2 full body resistance circuits per week
- 2 HIT/SIT with one SIT session of 4-8 wingate tests per week along with a HIT session ot 10 bouts of 1 minute all out sprint at 90% peak power.
- A weekly 250-kJ time trial
- A plyometric body weight circuit with a 30-s rest between exercise
Now from a programming standpoint I would argue that this protocol is not designed to maximize muscle gain but it is a good way to provide full body stimulus and really utilize all three energy systems during a week.
Pedometers were also used and participants averaged around 10,000 steps a day.
The rate of exercise compliance was 96% in the study.
The author’s used a unique approach in this study where they measured body volume using the BodPod, measured body water using Bioelectrial Impedance, and determined bone mineral density by DEXA.
Strength and Muscular Performance
Isometric knee extensor force was measured using a dynamometer. Leg strength and upper body strength were measured using a leg press and a bench press. Muscle endurance was assessed using a 1 minute pushup and sit up test).
Aerobic and Anaerobic Testing
Aerobic capacity was tested using a VO2 max test while a Wingate Test was used to test anaerobic capacity. The 250 kJ time trial test was also used.
Blood and Urine Measures
Blood and urine were collected to measure blood and urine metabolites as well as a panel of hormones
As expected in a 40% calorie restricted diet, both groups lost body weight with similar weight losses between groups.
Now here is, in my opinion the big result from this study. The LBM stayed the same in the CON group but increased in the PRO group. Meaning the PRO group lost fat and simultaneously increased LBM.
There was no difference between the groups in regards to strength or performance gains. There were small improvements in strength, aerobic, and anaerobic capacity in both groups.
Not surprisingly there were no real differences between the groups in regards to the blood and urine panels. However there were some big differences with respect to the time of the study. In both groups, there were large decreases in total and free testosterone, likely a results of the large calorie restriction. Also there were decreases in IGF-1, and insulin. Conversely we see an increase in the hunger hormone Ghrelin, not suprising given the severe calorie restriction present. Additionally cortisol also increased in both groups.
Also, the higher protein group saw no detrimental effect in in kidney function as measured by creatinine clearance. We do see increased blood urea nitrogen in the PRO group. Also, you see a small increase in eGFR (~5 ml/min/1.73m2) in the high protein group and something to consider as it does indicate increased filtration. This is now the second study to show the same thing in higher protein intakes in young men.
*I know this is a tautology but I use it intentionally for illustrative purposes.
** We could have also put caloric deficits in here as well but it creates a more “muddy” picture.
***Now here is the rub with study 2. If you compare the caloric intake between the overfeeding study and the “40%” caloric reduction study we actually observe similar protein intakes between the two studies (see table below). Now we need to take into consideration the two populations. In the overfeeding study there were 11 females and 37 males total and the mean participant mass was~75 kg. In the calorie restriction study there were only males and the mean participant mass was ~100kg. This may make up the discrepancy and explain the similar calories in the different context.
**** Given the nature of this population it is indeed possible that these participants were detrained, not untrained. This would present a fairly big caveat to the results in light of recent work in the field regarding “muscle memory”.