When Did ‘Anabolic Windows’ Become a Thing?

Trainee One: “Drink a protein shake within 30 minutes of training or else”

Trainee Two: “Why, what happens?”

Trainee One: “You’ll lose all your gains and the workout will be wasted.”

Yes, this was a conversation I encountered multiple times as a teenager training in the 2000s. Sometimes I was Trainee Two, asking good questions in the face of silliness but, all too often, I was Trainee One spouting knowledge.

The idea that I needed protein within thirty minutes of lifting weights ‘or else’ was pervasive during my early years of lifting and was often explained with reference to a vaguely defined ‘anabolic window.’ The anabolic window was the period when the muscles were primed to gobble up protein and get bigger. If you didn’t consume protein within thirty minutes of working out the window would shut and your gains would be lost forever.

In simpler moments, I often imagined this window shutting like a bank vault. Once it closed, it closed. Eventually, my bus home from the gym began to run late and, when I missed my ‘anabolic window’ for several weeks and still miraculously got stronger, I began to relax on the whole thirty-minute thing.

How young Conor imagined the Anabolic Window


But advertisers did not. Claiming that anabolic windows were indeed a thing and that they even had research (actual research…. not just supplement research!) to back these claims, anabolic windows were in vogue during the 1990s and 2000s. Today’s post explains how this happened and how, thankfully, it is a little more complicated than our fictitious trainee may have realized.

The Early Research

Research on the anabolic window, and its popularisation, needs to be split between two strands – one looking at glycogen levels and the other on muscle protein synthesis (MPS). For a minute there, I suspect some readers thought Conor was an exercise scientist as opposed to a historian of exercise. Oh to be skilled in science talk, how much easier funding applications would be (for the scientists, I jest!).

I am not qualified to speak on what glycogen or MPS are, although I will be speaking about how these concepts were utilized soon enough. Thankfully two very well-known and skilled exercise scientists, Brad Schoenfeld and Alan Aragon, have delved into the scientific origins of these concepts. In a series of papers and popular posts, the duo cited the 1980s and 1990s when papers about glycogen replenishment began to influence fitness practices.

The idea was that glycogen in the muscles (which provides energy – again… not a scientist), drains during a workout. Eating after a workout can replenish these glycogen levels. This can help with recovery. During the 1980s, and certainly well into the 2000s – as John Ivy’s and Robert Portman’s 2004 book Nutrient Timing: The Future of Sports Nutrition demonstrates – this helped popularise the idea that nutrient timing was incredibly important.

Concurrent with scientific studies on glycogen, were those on MPS. Much like research on glycogen, work from the 1980s and 1990s on MPS seemed to suggest that a post-workout meal/susbtance could help replenish MPS quickly and, in doing so, help to increase one’s muscle mass. One of Schoenfeld and Aragons’ papers described it thusly

The concept of nutrient timing was originally based on short-term studies showing superior increases in muscle protein synthesis (MPS) when amino acids were consumed in the immediate postworkout period versus delaying ingestion

The duo went on to state that initially, scientific studies seemed to confirm the idea that anabolic windows were indeed, ‘a thing.’ Bridging these two separate ideas together – glycogen and MPS – were some studies that seemed to suggest that combining protein and carbohydrates in a post-workout meal would improve the muscles’ ability to absorb protein under a noted phenomenon (which please God don’t make me explain) known as insulin spiking. By the early 2000s, scientific literature was translated into the fitness industry with a simple message – the quicker you injest protein and carbs after a workout, the bigger your muscles will grow and the quicker you will recover.

Just as an aside, expert creep is a real and noted phenomena. In essence it is what happens when someone with a Ph.D. in one field begins to express their expertise in another. An example would be those economists who claim to understand health trends or politics because ‘they just deal with cold facts’ as opposed to others who deal with a lifetime specialising in one topic. Another example is me, in the above paragraphs, trying to explain complex phenomena. I will, however, highlight my extreme ignorance, beg forgiveness for mistakes and also direct you to places like MASS, Examine.com and Stronger by Science for actual expertise.

With that out of the way, onto what I know…

How the Fitness Industry Interpreted Science

So to recap, by the early 2000s, it seemed like the ability to quickly consume protein after a workout was beneficial. Depending on how well scientific findings were translated into the public domain (which has historically been just awful), trainees were told that anywhere from 30 minutes to two hours post-workout were a sweet spot.

Replace Homer Simpson with the media and the federal agents with scientists and you get the idea…

This was a huge boon to fitness manufacturers but, to understand why, we need to discuss two things – the ‘Weider Research Lab’ and the ‘Pioneers of Protein.’ For readers of Randy Roach’s wonderful work, Muscle, Smoke and Mirrors, they will remember a short passage about the ‘Weider Research Laboratory’ endorsement which tended to feature on Joe Weider’s bodybuilding supplement advertisements from the 1970s onward.

The running joke within Weider’s vast bodybuilding empire was that the door to his famed laboratory led to the broom closet. Weider was not unique, as evidenced by multiple FDA investigations into supplement claims from the 1970s. Individuals selling supplements to consumers often exaggerated or lied about how effective their supplements were. Shock horror, I know. Thank god we have learned the error of our ways etc. etc.

Why does this matter? For decades, supplement manufacturers used dud science, or just straight up lied, when it came to their supplements. Then, all of a sudden, there appeared to be actual scientific studies – not just make believe ones – which seemed to suggest protein powders were useful.

This leads us to point two…the ‘Pioneers of Protein.’ This was an article written by historians John Fair and Daniel T. Hall on the early origins of protein powders in the United States. As we covered in a separate post, Fair and Halls’ article recounted the story of mid-century nutritionist Paul Bragg, and his meeting with York Barbell manufacturer, Bob Hoffman.

Long story short, Bragg wanted to create a supplement with Hoffman and presented Hoffman with some simple, but effective logic. Hoffman could only sell a barbell once, at most twice, to a consumer. He could, however, sell supplements on a monthly, or even weekly basis. Supplements were thus far more lucrative than equipment could ever be, provided the popularity was there.

The ability to sell supplements on a regular basis was profitable… and funnily that observation continues to hold true. Scientific research seemed to prove that protein post-workout was important – and what was easier to consume than a protein shake? More than that, trainees were told that protein had to be ingested after every workout – thus protein could be sold on a regular basis.

The scientific work on the Anabolic Window was like manna from heaven to manufacturers. Not only do these rubes (i.e. all of us) have to consume protein each time they lift weights, they could point to honest scientific literature.

Abusing the Anabolic Window

Perhaps abusing is the wrong term but the industry lost the run of itself with this. Particularly important was the idea of ‘losing’ gains by missing the anabolic window. A common piece of advice, as evidenced by this Muscle and Strength post, was that the window shut (I imagine forcefully) two hours after a workout. This actually went against some of the published research at this time which noted that, while it was likely beneficial to ingest protein and carbohydrates soon after working out, there was no hard and fast time. Others, did however, suggest strict timings.

There was a beauty about how simple it seemed and, supplements reigned in on it. Check out this promotional video featuring the vastly underrated Marcus Ruhl talking about the best supplements for the anabolic window in 2012

Such interviews were commonplace and always done within the context of justifying the use of supplements. It was just enhanced bodybuilders like Ruhl, either. In 2004, Ironman published an interview with drug-free Pro bodybuilder Jeff Willet which included the following endorsement of the anabolic window

One of the things I notice when I look at your daily menu is that you eat four postworkout meals. Wow! It makes total sense, and I can see how that’s one of the reasons for your success. You take full advantage of the postworkout anabolic window. Most guys do one or maybe two meals. I’ve seen pros go to a restaurant after a workout but not really take advantage of getting an anabolic surge.

JW: Exactly! That’s one of the big things we stress, based on Paul Cribb’s Anabolic Nutrient Timing Factor. (Paul is one of the researchers at AST Sports Science). You hit the nail on the head’taking full advantage of the anabolic window and the all-important surge of whey isolate at that time in the presence of high-G.I. carbs. A lot of people miss the boat when it comes to that.

DY: I’ve written about the anabolic window for IRON MAN, so I know its value. But you’re taking it to a higher level with four postworkout feedings. What’s your training program like?

I think these examples do a good job highlighting how pervasive, and even obvious (!), this idea seemed. Indeed it lasted for several years and, in many quarters, the protein shake immediately after the workout remains the ‘done thing.’

Science did, however, evolve, and provide more nuance. Alan Aragon has a very nice visual illustration of best practice now and while there is a peak period to ingest nutrients around workouts, it is more nuanced than 1 hour after you workout or you wasted your gains.


I would love to discuss how companies reacted to the changing science by reforming their ways and embracing nuance when it came to advertising claims. We all know that isn’t true so instead I will end by citing the importance of this story. While creatine and previous supplements came with scientific backing I would argue that the pervasiveness and the ubiquity of the ‘anabolic window’ was far stronger.

This was, I would argue, one of the first moments in which sport science, and actual studies, were adopted by the industry and trainees on mass. It occured at a moment when science backed training was beginning to flourish online and a moment when supplement manufacturers were seeking to catch up. The result was an unusual marriage between scientists, bodybuilders and entrepreneurs.

As always… Happy lifting!

2 thoughts on “When Did ‘Anabolic Windows’ Become a Thing?

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  1. CONOR…once again, your self-written posts (y’know I’ve taken to task some of your guest contributors’ stuff, lol) doth gladden my 67-year-old jaded heart.

    I’ve felt I’ve had to spend too much time during the past 20 of my 52 years in bodybuilding educating beginners, the uninformed, and the fitness-marketeer-industry-misinformed to focus on THE LONG TERM, the overall of consecutive years of consistent training/eating/recuperating, instead of on the short term “windows”. I’ll often summarize with this practicality:

    “The human body inevitably hits its drug-free genetic hypertrophy ceiling in the long term of three to five years. And, that process isn’t dependent upon what occurs during short-term windows of hours, but upon the long-term constantly balancing and rebalancing metabolic flux occuring over weeks, months and years. So, EVEN IF there’s a SIGNIFICANT optimal hypertrophy short-term window for, say, nutrition, the worst that missing those short-term windows will mean is it that gains might occur slower. At sub-optimal conditions, a body might need, say, five years instead of three years to hit its genetic ceilings. But, after five years, it won’t have mattered…because, unless you plan to quit bodybuilding after reaching your genetic potential, you’ll spend the subsequent decades doing maintenance bodybuilding anyway. So, quit agonizing over short-term nutrient windows; instead, ensure you get adequate protein, calories, and nutrition per DAY, and relax in knowing that in the long run of three to five consecutive years, you will reach your maximum genetic muscle potential.”

    1. Haha glad to have won you back Joe. I agree with you on misinformation, and I am more anxious about the need to be clear on expectations given the ease of steroid use these days. I have met plenty of teenagers now using SARMs, peptides and ‘old fashioned’ PEDS, which is worrying

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