Struggling with your weight? Get active and improve your health with high intensity interval training!

The Bottom Line

  • People who are overweight or obese are at increased risk of developing serious health problems such as heart disease, type 2 diabetes, and cancer.
  • High-intensity interval training (HIIT) appears to be an effective way to decrease risk factors for chronic disease, particularly in people who are overweight or obese.
  • HIIT is most effective when performed at least three times a week for more than 12 weeks.

If you’re carrying a little extra weight, you probably already know that exercise will be important to achieving your weight loss goals. You may also feel overwhelmed by the many exercise fads and trendy workouts that promise to transform your body. And really, how could you possibly fit one more thing – exercise – into your already packed daily routine?

The number of people who are overweight or obese has reached epidemic proportions (1). In 2014, 20.2% of Canadian adults – or 5.3 million people – were considered obese, while 40% of men and 27.5% of women were overweight (2). Being overweight or obese is not just about how you look. In addition to impacting daily life through symptoms like fatigue, joint pain and breathing difficulties (1), being overweight or obese puts you at increased risk of developing health problems such as type 2 diabetes, heart disease and cancer (1;2;3).

So, what can people who are overweight or obese do to improve their health? The short answer is still…exercise! Unfortunately, the number one reason people say they can’t stick to an exercise regimen is that they’re just too busy (4). But what if the benefits of exercise could be achieved in less time (5)?

Enter high-intensity interval training, or HIIT for short. Simply put, HIIT involves short bursts of intense exercise interspersed with longer periods of slower activity as recovery time (6). Some examples of HIIT include rotating between running and walking, sprint cycling and rest, or swimming and rest (5).

But is HIIT the miracle that we have been looking for?

What the research tells us

Research shows that, in overweight and obese adults, both short-term and long-term HIIT can effectively decrease risk factors for chronic diseases such as heart disease and type 2 diabetes. After less than 12 weeks of HIIT, people who were overweight or obese saw improvements in their waist size, diastolic blood pressure and blood sugar. While blood sugar reductions were not sustained, people who practiced HIIT over the longer term (for 12 or more weeks) saw additional improvements in systolic blood pressure, percent body fat, and resting heart rate. Maximum benefit was achieved when HIIT was performed at least three times a week for 12 or more weeks (5).

If you feel pressed for time, HIIT may offer an effective exercise alternative for improving health and reducing risk factors for chronic diseases in adults who are overweight or obese.

Get the latest content first. Sign up for free weekly email alerts.
Author Details


  1. Harding M. Obesity and overweight in adults. [Internet] 2015. [cited November 2017]. 
  2. Statistics Canada. Overweight and obese adults (self-reported), 2014. [Internet] 2015. [cited November 2017]. Available from 
  3. Tjepkema M. Health reports: Adult obesity. Toronto (ON): Statistics Canada; 2006. Vol. 17, no. 3. Available from: 
  4. Reichert FF, Barros AJD, Domingues MR, et al. The role of perceived personal barriers to engagement in leisure-time physical activity. Am J Public Health. 2007; 97(3):515-19. doi: 10.2105/AJPH.2005.070144.
  5. Batacan RB Jr, Duncan MJ, Dalbo VJ, et al. Effects of high-intensity interval training on cardiometabolic health: A systematic review and meta-analysis of intervention studies. Br J Sports Med. 2017; 51(6):494-503. doi: 10.1136/bjsports-2015-095841.
  6. Laursen PB, Jenkins DG. The scientific basis for high-intensity interval training: Optimising training programmes and maximizing performance in highly trained endurance athletes. Sports Med. 2002; 32(1):53–73. 

DISCLAIMER: These summaries are provided for informational purposes only. They are not a substitute for advice from your own health care professional. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the McMaster Optimal Aging Portal (

Many of our Blog Posts were written before the COVID-19 pandemic and thus do not necessarily reflect the latest public health recommendations. While the content of new and old blogs identify activities that support optimal aging, it is important to defer to the most current public health recommendations. Some of the activities suggested within these blogs may need to be modified or avoided altogether to comply with changing public health recommendations. To view the latest updates from the Public Health Agency of Canada, please visit their website.