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Does Having A Higher Body Fat % Make You Less Anabolic?

Eddie Hall Weight Loss Transformation

Should I bulk or cut first? Has been a common conundrum since the dawn of the online fitness world. It was often a heated debate on back in the late 2000s.

Many people believe that getting leaner prior to a bulking phase can improve your ability to build muscle due to an increase in insulin sensitivity. The theory is that as your body fat gets higher, your muscles become less responsive to insulin which means nutrients are diverted away from the muscle. This having the flow on effect of less hypertrophic (muscle building) potential. Therefore, cutting before a bulking phase and/or periodically throughout a long bulk phase could improve overall gains in lean mass. 

But does this theory really check out? We have a mechanistic hypothesis but does it really work like that in practice?

Stronger By Science published a review specifically on this topic last year that turned the broscience into actual science and addressed this question perfectly. 

Stronger by Science

The Stronger By Science Review & P-ratios 

The review looked at this concept through the use of P-Ratios. 

A P-ratio being the change in fat-free mass divided by the change in total body mass. 

So basically an easy way to put a scoring system on how much body fat versus lean mass had been gained during a bulking phase. 

A high P-ratio = You have put on weight with minimal fat gain 

A low P-ratio = You have put on weight but with substantial fat gain 

This system starts to fall apart a bit when you have very poor outcomes (loss of lean mass with weight gain) and really great outcomes (loss of body fat with gains in lean mass leading to overall weight gain) but we won’t go to that much complexity here. 

This is still a great way to view these changes in body composition. 

Eric Trexler, the author of the review, mentioned two observations that really had him second-guessing the idea that being leaner = better gains in lean mass. 

These were:

  1. Bodybuilders directly post show (objectively some of the leanest athletes you will find) seemed to gain fat very rapidly post show and not too much muscle mass (aka have a low P-ratio). Based on the above theory, post show bodybuilders would be super anabolic and be able to pack on muscle mass, but that is not what we see in a real world setting. 
  2. Super heavyweight powerlifters and top strongmen have some of the highest rates of lean mass amongst athletes, yet usually have a substantial amount of body fat. They also tend to continue to make gains in lean mass whilst having a lot of body fat. So the theory really isn’t checking out here either. 

Where Did This Theory Start?

The review also critically analyzed the research that many had been pointing to, to back up their arguments in favor of this hypothesis.

This overall theory stemmed from a review by Forbes in 1987. Which was a research review looking at body composition changes of people who were in an extended calorie surplus and gaining weight. 

The paper summarizes that those who were the leanest experienced greater gains in lean mass than those who had more body fat. So it sounds pretty confirming of the above theory.

BUT there are a couple of issues with extrapolating this data to those who are resistance training and looking for the best body composition outcomes during a building phase.

Number 1: None of the data included in the Forbes review was in populations who participated in resistance training. So already it isn’t comparable to a gym bro looking to get some lean gains. Without resistance training, there is not enough stimulus to the muscles. They would have no reason to adapt and grow. 

Number 2: Some of the data actually came from recovering anorexic patients. You would expect greater gains in lean mass in very underweight people in a calorie surplus due to the fact they would have lost a lot of critical muscle tissue previously. So the body will prioritize replenishing these muscle stores required for basic physiological functions.

In fact, after this data was removed from the analysis, there was insufficient evidence of a relationship between the composition of weight gain and initial body fat levels. This is very telling. 

Number 3: Other data came from weight regain studies after a starvation diet and extreme, rapid weight loss. This would likely have a similar effect on results as the above-mentioned data. In that, there was likely a significant amount of lean mass lost during the overall weight loss and it may therefore be easier to regain afterwards. 

So basically the research that many were using to justify this theory, can’t even be applied to people who are resistance training in the first place.

Woman Deadlifting

Looking At The Research 

Another argument in support of this theory is that research has shown that people with higher body fat seem to have a reduced muscle protein synthesis (MPS) reaction to protein feeding. However, they also seem to have a reduced muscle protein breakdown. So the overall effect on protein balance likely isn’t significant. 

We also don’t see a lack of lean mass in obese people, in fact we see higher levels of lean mass in people with a significant amount of body fat. Meaning that a calorie surplus is one of the biggest factors in lean mass gains, not starting body fat levels. 

To put this into greater perspective, a paper published in 1999 compared the body composition of sumo athletes across four different levels of competition. If there are any athletes that would clearly demonstrate that lean mass gains become more difficult with more body fat, it would be sumo competitors. 

However, what this research found was that the lowest ranking competitive class had similar body fat percentages to the highest-ranking class even though the higher ranking class was on average more than 50kgs heavier. 

This pretty clearly demonstrates that lean mass gains can be plentiful even when high levels of body fat are present. 

Sumo wrestlers anabolic lean mass body fat percentage

Research from American football players is also a good example. Stodden et al categorized college football players into three groups: “skill” (generally lower body-fat percentages), “linemen” (generally higher body-fat percentages), and “big skill” (typically in-between).

The linemen started the invention with much higher body fat than other positions yet after one year had gained the least lean mass out of all three groups. They even lost the most fat mass. Similarly, the big skill group gained the same amount of lean mass as the skill group. 

So not only are we not seeing a negative correlation between starting fat mass and gains in lean mass. We are actually seeing more positive results in players with a greater amount of body fat to begin with. 

Now, this isn’t also to say that more body fat = more gains but it does disrupt the notion that body fat impairs muscle growth. 


So does baseline body-fat percentage predict how much fat mass or lean mass a person will gain over the course of a building phase coupled with resistance training?

Not based on the current research we have. If anything those who are always aiming to be leaner before bulking are probably wasting precious time where they could be gaining lean mass. 

Weight gain is directly related to the degree of overfeeding aka the size of the calorie surplus

The makeup of that weight gain in relation to % body fat versus lean mass gain is dictated more so by genetics, training stimulus, recovery factors (i.e. sleep) and how much muscle mass you already have. 

The mechanistic theory of body fat and insulin sensitivity in relation to body composition changes is basically the carbohydrate-insulin model of obesity revisited. 

Starting body fat levels dictate body composition outcomes during a bulk as much as carbohydrates cause obesity. 

The evidence base for this hypothesis is also based on populations that aren’t even doing any resistance training. 

So don’t get too caught up in p-ratios and having to “cut before you bulk”.

By Leah Higl

Leah is an accredited practising dietitian from Brisbane. She also competes as an under 75kg powerlifter with Valhalla Strength Brisbane. As both an athlete and dietitian, she spends much of her time developing her knowledge and skills around sports nutrition, specifically for strength-based sports. Although, she works with a range of athletes from triathletes to combat sports and powerlifting. Leah also follows a plant-based diet and her greatest passion is fuelling vegan/vegetarian athletes and proving that plant-based athletes can be just as competitive as their non-vegan counterparts.​