Does Soy Build Muscle? Exploring the Science Behind Protein Choices

Think soy burgers are as good as beef for muscle growth? They’re not. Here’s the science behind the difference.

Does Soy Build Muscle? Exploring the Science Behind Protein Choices

Soy burger plant overshadowing a muscle lifting weights

Think soy burgers are as good as beef for muscle growth? They’re not. Here’s the science behind the difference.

Muscle health is on your radar.

But so is heart health, bone health, eye health………. basically you’re striving to keep it together so you can enjoy life i.e. you want BETTER BODY CHEMISTRY.

The Role of Protein in Muscle Health

Muscles are MADE of protein, so you understand the imperative of sending in adequate levels to ensure they have the resources needed to maintain the status quo.

You’re all aboard with the guidelines, and ready to push for the recommend 1 -1.2 g/kg/day, but what protein should you be eating ?

Well official guidelines would be nudging you to eat plant protein………….

The pluses of plant based protein

It’s supposedly better for the planet and it’s definitely better for your heart since…….

Animal protein comes with ANIMAL FAT aka cholesterol.

And high cholesterol “blocks” blood vessels leading to DEATH and DESTRUCTION.

Motivated to DO THE RIGHT THING – you choose an Impossible Burger.

The Impossible Burger option

Yes, it is an ultra-processed but it fits the bill.

It’s looks like the real thing, tastes pretty close to the real deal and it’s made of plant protein. Specifically it is fashioned from soy which is considered to be a complete protein since it has all of the essential amino acids.

NOTE : Something that doesn’t happen with all plant protein sources.

PLUS Japanese people eat have been eating soy for centuries and they “all” live to be OLD.

Shout out to modern technology – it’s a MATCH !

Well sort of.

On paper, does soy build muscle ?

Yes. There are some differences in amino acid composition, between plant and animal protein, but soy has the all-important amino acid, leucine…

Leucine is an amino acid that punches above it’s weight when it comes to muscle protein synthesis (MPS). Nicknamed the LEUCINE TRIGGER and bros in the gym, it’s a big deal for gym bros hoping go bulk up during lifting sessions.

However, it’s not quite that straightforward. Biology never is. Lol.

Does Soy Build Muscle in a Real Meal?

It definitely is important if you are getting your protein from a smoothie, which is a little “artificial”, but if you’re getting protein, “naturally”, it is only part of the puzzle.

And this is where this study is interesting because it looked at what happens when you consume protein in a REAL meal.

In this case, the real meal is a hamburger patty. Three options were on the menu :

A 4oz beef patty.
A 4oz SBMA (which stands for soy-based meat alternative aka an IMPOSSIBLE BURGER).
A double whopper Impossible burger, amounting to 8 oz of SBMA

Here is an official breakdown of the composition of the 3 burger patties.

The leucine trigger is sort of covered in the 4oz version of the patty, but the 8 oz version NAILS it.

Throw it on the barbie

The research team invited 24 healthy to the lab to be tested. The participants included both males and females and the BMI’s ranged from 20-32. They were all relatively young, ranging in age from 18 to 40, so when it comes to building muscle, the dice was loaded to favor the people in the study.

This is not the case if you’re an “oldie”. Unfortunately, if you are no longer a “spring chicken”, you are far more likely to be short of muscle. The muscle building struggles of the aged is attributed to a phenomenon known as “anabolic” resistance.

Not familiar with the term ?

Science is yet to fully explain the mechanisms behind it, but it is a universal problem – it takes SO MUCH MORE, for oldies to build muscle. I think the problem is related to delivery issues, sparked by insulin resistance, but that is a story for another day.

Primed for muscle protein synthesis

These guys in this study were primed to build muscle. And this is what the team tracked. To do this they infused radioactive amino acid tracers and then tracked where they went, both when there was no dinner and after the different hamburger dinners. Here are the results.

The level of protein synthesis following consumption of three different patties

Beef wins : The 4 oz beef patty stimulate whole body protein synthesis as expected.
Soy struggles : The 4 oz Impossible Burger, NOT SO MUCH.
Double up : No worries, the 8 oz Impossible Burger ticked the boxes. Yes but…….

The odds that someone eating TWO patties at dinner is probably not so high, so although IT WORKS, will it ACTUALLY HAPPEN ?

Most people would stop at one – assuming that they are getting the “same” or “more” benefits from the soy burger.

But this research suggests they’re NOT.

Why not ?

The Problem with Soy-Based Meat Alternatives

The team did have a stab at answering this, although this was not the primary goal of this research. The soy patty, despite being ultra processed ends up being a little harder to digest, because soy protein is well……………..TOUGHER. This translates to lower levels of amino acids circulating, including the all important leucine. And this ends up being enough to matter.

Here is the time line for the amino acid rise in the three conditions.

Graph showing amino acid levels following consumption of different hamburger patties

The soy peak in the case of the 4 oz soy patty is lower. And in the case of the 8 oz soy patty, the peak is higher, but delayed in comparison to the beef burger patty.

This is good to know if you’re opting for vegan meat alternatives and you’re getting on in years…

Soy builds muscle only at higher doses

They might taste the same, but their biology is a little different, so to get the equivalent benefit, you should put a little bit more protein on the plate.

NOTE : Just for the record, you need the “extra” protein, not extra calories !

Because muscle’s need protein.

And muscle health is HEALTH.

You want to do what you can to maintain your muscle mass.

Work them. Feed them. Juice them.

Keen to dive deeper into muscle health, visit the muscle library page.

The anabolic response to a ground beef patty and soy-based meat alternative: a randomized controlled trial. Am J Clin Nutri (2024) 120(5):1082-1092. David D Church, Katie R Hirsch, Shiloah A Kviatkovsky, Joseph J Matthews, Arny A Ferrando, Gohar Azhar, Robert R Wolfe.