Believe it or not, there isn’t a simple answer to this question. There’s some context we need to discuss, both with the science and with your expectations.

Getting and keeping a body and life you love is a long-term play. If you’re starting with a quick-fix mentality, you’re going to experience nothing but frustration.

With that said, there’s nothing wrong with wanting to know how fast your body is likely to change after you start putting in the work. So, let’s take a look at what the science says…

How long does the science say it takes fitness benefits to show?

There are a lot of micro-benefits that happen behind the scenes almost immediately after engaging in a fitness practice. Improved insulin resistance is one of them.

I assume you’re most interested in the macro view though. You want to know how many days, weeks, or months you should expect body composition changes to take.

There’s a few different areas we want to look at here:

  • Reduction in body fat
  • Muscle growth
  • Gains in strength
  • Improvements in stamina
  • Improvements in flexibility & agility

Yes, there are other data points we could look at, but these five should cover the most popular factors.

In terms of reducing body fat, it’s important to understand that the body is always burning and storing fat. However, you can certainly improve fat oxidation as well as the rate at which your body lets go of stored excess fat.

Improvements in fat oxidation have been shown in pre-breakfast aerobic exercise, sprinting, and interval training. I’m sure these are repeatable results in many different activities, but these are the ones I found studies for.

Muscle growth happens pretty quickly, relatively speaking. You’ll likely notice gains in strength sooner than gains in size. All of this, of course, is highly dependent on the type of strength training you choose to engage in.

For example, lower volume, higher-intensity training has been shown to be more effective for muscle growth than high volume, low intensity work. If you want to change body composition faster and more radically, lift heavier for less reps. Put in work for 10-12 weeks before you start checking for visible results.

Improvements in stamina can be made much more quickly. Sprinting, interval training, and distance training all improve VO2Max considerably. We’re talking 2-4 weeks for pretty significant improvements.

Across the studies I looked at, significant improvements in flexibility can be had in as little as 4-5 weeks. One study on a 12 week Pilates program showed significant improvements for that activity as well.

Fitness benefits are closely linked to nutrition.

In one of the first articles ever published at Rebooted Body, I made it a point to note that nutrition is the biggest factor in body composition change. If you’re not getting your diet on point, then you have no business worrying about how fast you’re going to see results from your fitness practice.

If this is an area that you need help with, along with the other important lifestyle and self-care habits that play a major role in your success, then I’d highly recommend you do a 90-Day Total Body Reboot.

Every body is different.

You can’t rule out bioindividuality in a discussion like this. When I say that it probably takes 10-12 weeks to see significant changes in muscle size, that doesn’t mean some people won’t see changes sooner or later than that.

Bioindividuality doesn’t just affect the time it takes to see improvements, but the amount of improvement as well. You can put two people on the same diet and fitness regiment and they’ll have different results at the end of 12 weeks. That’s life.

The lesson here is to not put too much weight in what studies say or what you’re observing in other people. Respect that your body is unique and will respond accordingly.

With that said, it’s okay to use the averages and expectations to determine if a protocol is working. If you’ve been putting in the work and you’re not seeing results, it’s quite possible that something needs to change.

Your expectations must be realistic.

What I see all day long on Pinterest, Instagram, the media, and plastered all over fitness and gym websites is not realistic. Our expectations, hopes, and dreams are often manipulated by these outlets.

Instead of approaching a game plan with realistic expectations, people are often approaching it from a perfectionistic, unachievable, and unsustainable frame of mind.

If the changes you’re hoping to see in your body involve six packs and “being shredded” then you’re going to have to obsessively dedicate your life to achieving that (unless you have seriously amazing genetics).

When we work with clients, one of the biggest obstacles is helping them shed this unrealistic programming. It’s a leading cause of failure because it causes endless friction and creates goals in their mind that they can’t accomplish.

Which brings me to…

Your relationship with food, body, and Self matters.

It’s very easy to have a body you love and a life you hate. It’s what happens to people who win the dieting game. It’s what happens to people who find self-worth through their appearance, weight, etc. It’s what happens when you have a poor relationship with food, body, and Self.

Through our research and interactive assessments, we’ve found that 70-80% of men and women seeking advice about nutrition and fitness have a dysfunctional relationship with food, body, and Self (you can evaluate yourself if you want). It’s very easy to make this worse by following bad advice or having unrealistic expectations.

The goal, instead, should be to heal your relationship with food, body, and Self and in turn become *less* obsessed, oppressed, and unhappy.

How fast you get fitness benefits doesn’t matter if your plan is unsustainable.

Intuitively, you know this. But, that doesn’t stop people from crawling back to the legacy dieting and fitness industry, only to be foiled again. There’s an epidemic of people engaging in fitness practices that they don’t enjoy, that are unsustainable, that are injurious, or that flat out don’t work that well.

A good fitness practice is one that is infinitely sustainable, is functional, is engaged with daily, and is intrinsically motivated. Yes, that means it’s possible to have a fitness practice that doesn’t require willpower or discipline. In fact, we have a free guide on building a fitness practice like this at

Founder of Rebooted Body and host of The Rebooted Body Podcast. Kevin helps men and women finally get a body and life they love with his unique blend of real food, functional movement, and psychology. To work with him personally, choose a program.

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