Exercise, Interval Training and Weight Loss – the Basics

In the interest of furthering the conversation about serious weight loss options it is useful to review the current research as it relates to the latest marketing trends. Often there is a significant gap in the health and fitness industry between what the empirical evidence shows to actually work and what a company with vested interests can sell. This leads many of us to be cynical with regards to the health and fitness industry as whole and rightly so. It seems there are more snake oil salesmen than honest product offerings, and although this can be attributed to the nature of the product to some degree, (selling a better self-image is bound to be personal for those buying it), a critical review of the research may help un-muddy some waters.

HiiT training is the latest fad. It stands for High Intensity Interval Training, and is defined by bursts of maximum intensity exercise framed with active recovery. Active recovery means you are not completely at rest, but are working at a lower intensity usually within your aerobic threshold. There are many forms this can take, from 7 minute a day workouts you can buy online to trainers in specialised gyms offering forty five minute workouts. As you can imagine, the results will vary depending on the delivery, but below is a summary of the research as it pertains to high intensity training. Read it and make up your own mind.

Do We Need Exercise For Weight Loss?

First let’s clear one thing up. Is exercise actually important in a weight loss program? Many people, (often trying to sell something or repeating something they have not understood), will recite lines like “Weight loss is 80% diet and 20% exercise.” This is a misleading statement for many reasons. First, it doesn’t state what the proportions relate to. 20% of calories? 20% of your effort? 20% of the dollars you spend or the minutes you put into it? The interpretations are endless because the statement doesn’t set clear parameters. And that is because there is no research behind that statement – it’s about as useful as the 7 Signs of Aging are.

Second, even if we assume the author of this statement is referring to the amount of effort one needs to divest in both diet and exercise as a proportion of total effort in a weight loss program, this statement assumes that all bodies are created equal AND that all lifestyle habits are currently equal. For example, I exercise at least daily, sometimes twice a day. My diet is not great and I consume too many calories at times. For me the amount of effort I should dedicate to diet in order to lose weight is 100%. My friend on the other hand has become a little sedentary in her new job. She has put on a few kilos despite the fact her diet has barely changed probably because her metabolic requirements are less now that she is less active. So for her 100% of the effort should be theoretically dedicated to exercise. This study gives a great summary about the link between diet, exercise and weight loss.

There are some people that would argue that a drastic reduction in calories will inevitably result in weight loss regardless of exercise habits. However, the empirical evidence has repeatedly shown that this is not the case. This link is a particularly interesting study and the comment at the bottom attempts to explain the role of diet and exercise in resting metabolic rate. In short, exercise has a positive effect on metabolic rate in a way diet can’t. In fact many diets, most of them fads, that advocate for low calorie consumption, (these are known as Very Low Calorie Diets or VLCDs), will have a negative effect on metabolic rate and make it harder to lose weight.

In short, exercise plays a vital role in a continued and sustained healthy weight loss program. While it is possible to lose weight through diet alone, it is difficult. And it’s even more difficult to maintain.

What is the Best Intensity Level for an Exercise Program for Weight Loss?

Dr Thomas Gunnarsson devised and studied a form of interval training which promised a fast effective workout. This took interval training and gave it defined parameters for each interval. The idea is that each minute is split into a low intensity 30 second interval, a medium intensity 20 second interval and a high intensity 10 second interval. These roughly equate to walk, jog, and run intensity levels but the theory can be applied to most forms of aerobic exercise. His peer reviewed paper found it was just as effective to employ 10-20-30 training as it was to do longer intervals of higher intensity and the subjects could work harder for longer.

The research has been replicated in many forms – Australian scientists at the University of Sydney found a two tiered interval program of 12 seconds low intensity and 8 seconds very high intensity for a total of twenty minutes was effective in weight loss when done at least three times per week. The Human Performance Institute in Florida also studied varying forms of HiiT and recommends a 12 station circuit with 30 seconds at each station and no more than 10 seconds rest. The circuit can be repeated 2-3 times for maximal effect. These are both versions of a Swedish form of interval training known as Fartlek, or speed, training which has been doing the rounds for decades.

So the research definitely supports interval training in various forms for increased performance, fitness and strength. But a more recent study from the University of the West of Scotland found that HiiT training in its purest form, (high intensity training for short periods of time), is less effective than traditional aerobic exercise for weight loss in obese individuals. It should be noted, however, that both groups lost a significantly significant amount of weight, and more importantly that the HiiT group exercised for just 63 minutes per week compared with 420 minutes per week for the aerobic group. There is still room for more research in this area, and it is possible that tweaking the number of minutes and intensity of exercise for a modified form of HiiT could result in greater weight loss.

That is what the research says. As an ex trainer, I am frequently asked about the best way to embark on an exercise program for weight loss. My answer is usually this; You need to exercise. You need to eat well. You need to do both consistently and indefinitely in order to sustain weight loss. Whatever exercise program you choose, make sure it is one you will stick to and that you enjoy, and most importantly that fits into your routine. And in terms of intensity, moderate forms of interval training allow you to exercise for longer periods at a higher calorie burning level. Work as hard as you can for as long as you can as often as you can and you will certainly see results.

One thought on “Exercise, Interval Training and Weight Loss – the Basics

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