Recently I’ve been asked to contribute to an article about the popular 30-day challenges. Of course I had heard of them, but I had never read any scientific publications about it. So, it was a nice challenge for me to come up with scientific explanations on a bunch of questions. Can you expect any results after 30 days? What are the consequences on risk injury? And what happens after 30 days? I pretty much came up with this…

The 30-day challenge:

What exactly is a 30-day challenge? Actually, several of those challenges exist, with a wide variety amongst them. The basic principle is to improve (almost) each day during a 30-day period. Each day you should perform more repetitions, or longer exercises. A variety of exercises could be incorporated. Popular ones are the squat and plank challenges. Often those exercises are performed with body weight as load. You don’t use additional weights and just increase the number of repetitions or duration. In the beginning, the body will see this kind of training as a strength training: your body isn’t used to perform those exercises. But after a while it becomes more of an endurance program. After all, your goal is to achieve a fixed amount of repetitions, which increases each day. Nevertheless, the weight or training load approximately stays the same. Therefore, most of the 30-day challenges are kind of a combination of both ends.

Should you take on the challenge? Let’s start with my advice: no. Go to a professional and make a plan with him/her! A professional takes multiple facets into account, making your training a long-term multi-disciplinary project. As it should be!

Does this mean that you shouldn’t exercise at home at all? No, of course you can do exercises at home! Just let your instructor explain to you what you should pay attention to and have him/her to fit you the right training schedule. We’re living in a sedentary society, meaning we sit way too much. A challenge might be a good way to get people off their couch or office chair. Many 30-day challenges sound promising, or at least make nice promises, but are they really that promising? I just don’t buy it.

Can you expect any results after 30 days?

The body is highly adaptable, including your muscles. No doubt that a month of exercising can have positive effects on your body. But are those differences really visible? A lot of people just want to lose some pounds before the summer comes or gain some muscle mass. If one of those is your goal before starting a 30-day challenge, you probably don’t like the answer. Changes in body composition often occur after several weeks of exercising (1,2). For example, the process of muscle improvements (build-up) will initiate soon after performing your exercise, but the true results in terms of muscle size will not be visible that fast.

But again, this doesn’t mean that there aren’t any improvements after four weeks! Your body is adapting faster and more rigorous than you think. Muscle strength, for example, will improve very fast by means of neural improvements. In other words: your body improves your muscle control (more) before improving the true size of your muscles (1,2). Therefore, 30-day challenge would be no more than just a start. And that’s one of the dangers of a 30-day challenge: people might achieve their goals and quit after that.

Regarding the other goal (‘losing fat’); weight loss can be initiated pretty fast. However, a major part of the initial weight loss is due to water loss, not fat (2). Still fat loss might be induced pretty quickly. The one scientific article I found was very positive regarding the 30-day challenge (3). However, the training schedule was not just a simple 30-day challenge. It even seemed to be a pretty complete training program.

Nonetheless, a simple internet 30-day challenge often is some kind of compromise between strength training and endurance training. No matter what your goal is, there’s always a better and more efficient training program than a general training challenge from the internet!

Why it’s not likely to work

One of the things that is often overlooked by people is nutrition. You can’t gain muscle mass if you’re not taking the right nutrition. Your muscle mass is a balance between constant muscle production and degradation. If you don’t exercise, the net balance can be negative. Exercise might turn this balance positive, however the body needs the right building blocks to do so. When your exercising without proper nutrition, the body isn’t capable of replacing and improving your muscles. The net result: a faster muscle breakdown. And even if your goal is to lose fat, your body still needs essential building blocks and vitamins etc. to stay healthy!

In previous studies, four training principles were distinguished: overload, specificity, individuality and reversibility (1). When applying those principles to 30-day challenges, most of these challenges won’t come out very well. A 30-day challenge is built on the overload-principle: every day the intensity of the exercise is increased. But this isn’t the same overload for everybody! Some people weigh more, some people weigh less. Some people have more upper-body weight, some have more lower-body weight. The training intensity might be too hard for one person, while too simple for another. And those are just a few examples. Safe to say that 30-day challenges aren’t very individually either. Another reason to ask a professional for help, instead of just following the hype!

The lack of specificity already was discussed before. First establish your goals, then base your training on them. Take in mind that a training is more than load, reps and sets or duration! One movement can often be executed in very different ways. How fast do you perform the movement(s)? What’s your position during the movement? A 30-day challenge doesn’t specify all of this. And then the last principle: reversibility.

What to do after the 30 days?

When you stop after a 30-day training, detraining is very likely to occur in a fast tempo. Detraining is often a faster process than training. Therefore, it’s essential to induce permanent lifestyle changes instead of just a simple training schedule for 30 days! Keep a training fun and effective by varying in exercises. Challenges often consist of only one exercise, making them boring and very one-sided. A bad example, which I found on the internet: 250 squats on day 30. 250 squats! This would be hard for everybody, not only for beginners. And someone who’s performing squats for 30 days, I still call a beginner. Some of the 30-day challenges are way too hard, which might result in high drop-out rates or nasty injuries.

Injury susceptibility

When performing exercises at home, the risk of injury likely increases. None is telling you when you perform the exercises wrongly. Especially when someone is exhausted, he or she might perform the exercise incorrectly. Take the example of 250 squats. First, it’s important to incorporate rest in your training programs to recover from exercises. Although, even with rest intervals, 250 squats seem to be undoable. Second, always remember that it’s better to perform less, but highly qualitative repetitions, instead of going for the high number of repetitions! And the latter is exactly what a 30-day challenge is based on…

And then there is self-overestimation. Probably the most stupid and dangerous thing you can do! Never think you can just start exercising at high-intensity level, especially not when you’ve always been very sedentary. People who never engaged in exercise (or a very long time ago) and who barely walk or ride their bike might be highly susceptible to heart failure when suddenly performing at high-intensity levels! Always start at a low intensity. Go for a walk a few days a week for example. Please just ask a professional instead of going blind on internet schedules.


A 30-day challenge might sound promising and an easy way of improving health quickly, but don’t be fooled. Although the idea of getting people off the couch by means of a challenge may initiate some awareness, it’s unlikely that it actually helps. The standard 30-day challenges are one-sided, too general, too hard, stop after 30 days and are without any form of guidance. All of which may lead to drop-out, injuries or worse!

My advice: ask a professional and make a training schedule with him or her! A professional knows what factors to take into account and looks beyond the 30 days. He or she can also help you with exercises which you might perform at home. Keep in mind that you want to initiate a life-long lifestyle change. Thirty days of exercising might have some positive effects, but it’s barely a start. Take all the above in consideration and you pretty much have a complete training schedule. It’s important to keep challenging your body, but please do this in a responsible way!

  1. Bruton A. Muscle plasticity: response to training and detraining. Physiotherapy. 2002;88(7):398-408.
  2. McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance. 7 ed: Lippincott Williams & Wilkins; 2010.
  3. Canon C, Culbertson J, Byrd M, Rasmussen C, Jung Y, Khanna D, et al. Effects of a 30-Day Fitness Challenge on Body Composition and Health Markers in Sedentary Women. The Journal of Strength & Conditioning Research. 2011;25:S34-S5.