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Can High Intensity Interval Training Help Suppress Appetite?

Published on September 18, 2013,

Most people would agree that exercise is generally a good thing but whether it actually helps weight loss is much less clear. Once reason is that exercising makes people feel hungrier and this in turn can make them eat more. However, new research discussed by Dr Briffa suggests one form of exercise – HIIT – might have the opposite effect and actually suppress the appetite. This is from Dr Briffa…

A US Marine Doing Pull-ups.

A US Marine Doing Pull-ups. (Photo credit: Wikipedia)

The heightened hunger that can come as a result of exercise does not happen to everyone, but my experience tells me it tends to be more common in individuals who engage in relatively prolonged exercise such as extended running or cycling. In my book Escape the Diet Trap I made the observation that ‘high intensity intermittent exercise’ (short, intense bursts of activity interspersed with longer periods of rest) tended not to make people hungrier.

Now, recently, a study was published which lends at least some support to these observations.

In this research, overweight, sedentary men were (at different times) subjected each of the following conditions:

1. continuous exercise at 60 per cent of maximum oxygen utilisation (VO2 max) for 30 minutes

2. 1 minute at 100 per cent VO2 max alternating with 4 minutes of 50 per cent VO2 max, repeated for a total exercise time of 30 minutes

3. 15 seconds of exercise at 170 per cent VO2 max alternating with 60 seconds at 32 per cent VO2 max for a total of 30 minutes

4. Rest (no exercise) for 30 minutes

After each condition, the men were fed a meal with a set number of calories. 70 minutes later, they were given access to food that they could eat freely. Food intake and activity levels were monitored on the day of each experiment and the following day (a total of 38 hours).

Interestingly, the intakes of the test meal 70 minutes after conditions 2 and 3 were lower than that when no exercise was taken (condition 4).

Also, energy intake over 38 was lower after condition 3 than after conditions 1 and 4.

Interestingly, I think, after condition 4, levels of the appetite-stimulating hormone ghrelin were lower, and blood sugar levels higher, than after the other conditions. Levels of lactate were also higher, and there is some evidence that lactate suppresses appetite [2].

This study was short, in that each condition was only tested once. However, there is at least some evidence here to support the idea that high-intensity exercise not only may not stimulate the appetite, but might even suppress it.

More (including references for the research) at:  Evidence suggests one form of exercise might actually suppress appetite

Twelve Minutes’ Exercise Per Week ‘Enough To Improve Health’ If You Do It The Right Way…

Published on June 7, 2013,

A new study into high intensity exercise suggests just 12 minutes of intensive exercise per week is enough to improve your health if you are overweight. This is from the Telegraph…

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Four-minute bursts of high-intensity exercise such as running on a treadmill, three times a week are enough to increase fitness, researchers found.

Overweight volunteers who undertook the regime for 10 weeks increased their body’s oxygen uptake – a measure of fitness – by 10 per cent and saw small decreases in their blood pressure and glucose levels.

Health guidelines generally state that we should undertake at least 150 minutes of moderate exercise or 20 minutes of vigorous exercise per week in order to stay healthy.

But the new study suggests that just 12 minutes of high-intensity exercise, spread out across three sessions, could be enough to keep us fit and healthy, researchers said.

The team from the Norwegian University of Science and Technology in Trondheim studied the effects of different exercise regimes on 24 men who were overweight but otherwise healthy.

Three times a week for 10 weeks, the men undertook bouts of “vigorous” exercise, which involved running on a treadmill at a speed which raised their heart rate to 90 per cent of its maximum capacity.

For half of the men the regime involved simple four-minute sessions, three times a week, while the other half completed three sixteen-minute sessions, each of which was divided into four-minute segments.

Despite carrying out different amounts of exercise, the results for the two groups were strikingly similar.

Oxygen uptake – the amount of oxygen the body can use during exercise – increased by 10 per cent in the four-minute group, and by 13 per cent in the sixteen-minute group.

Blood pressure and glucose levels lowered by similar amounts in both groups, but the more intensive sixteen-minute sessions was more effective at lowering cholesterol and body fat.

Writing in the Public Library of Science ONE journal, the researchers said that such improvements could lower the risk of death from conditions like heart disease and stroke.

“These data suggest that it may be possible to reduce cardiovascular mortality with substantially less exercise than is generally recommended, provided it is performed in a vigorous manner,” they wrote.

The researchers said the exercises could easily be incorporated into a daily regime, for example by walking quickly up six to ten flights of stairs or by walking up a hill with an eight to 10 per cent gradient.

More at:  Twelve minutes’ exercise per week ‘enough to stay fit’

Get Fit On Three Minutes Exercise A Week

Published on January 10, 2013,

We figure anyone interested in a low carb diet is interested in health and wellbeing generally and especially in getting the best results from your efforts. We think therefore that this article from the UK’s Daily Mail about short, sharp bursts of high intensity exercise is worth reading and thinking about…

High Intensity Interval Training from dailymail.co.uk

High Intensity Interval Training from dailymail.co.uk

Scientists at the universities of Nottingham, Birmingham and Bath say the secret is to commit yourself to three short bursts of highly intense exercise for 30 seconds each, with short rest periods between, in less than five minutes.

They claim early results are ground-breaking and may lead to conventional medical textbooks on exercise being torn up. Instead of sweating for hours, scientists say we should hurl ourselves around on an exercise bike or rowing machine — or even just run rapidly up and down the stairs at home.

After half a minute of wild exertion, we can collapse red-faced for 60 seconds, then do it all again. Three bouts like that means your exercise requirement for that session is sorted.

Late last year, the scientific team behind this regime launched a large-scale trial involving 300 volunteers to fully test their system. It could be just the tonic for couch-potato Britain.

For despite constant nagging from government and health professionals, the vast majority of us still don’t follow the official NHS advice to do at least 30 minutes of brisk exercise five times a week, plus two sessions of muscle-strengthening exercise such as weight-training, push-ups or heavy gardening.

More than 60 per cent of men and 70 per cent of women admit that they don’t manage that. Lack of time is our most common excuse.

As a result, millions of Britons suffer early death and unnecessary disability due to lifestyle illnesses such as diabetes and heart disease.

But the answer for many could be quick and simple.

The ongoing study is led by leading exercise expert Jamie Timmons, a professor of systems biology. The team call their system High Intensity Impact Training (HIIT).

So far, their tests on hundreds of unfit middle-aged volunteers in Britain and Canada over the past eight years have shown those three minutes of exercise a week deliver the same significant health improvements as can be achieved through hours in the gym or on the running track.

But scientists do not yet entirely understand why the short-burst exercise regime so profoundly boosts volunteers’ stamina and the fitness of their lungs, heart and blood vessels.

‘The truthful answer is we do not fully understand this,’ says Professor Timmons. ‘But a growing body of independent research shows this is the case and that the textbook explanation of the science of exercise requires revision.’

As for weight loss, the results from conventional long hours of exercise regimes often prove disappointing.

Typically, exercisers get themselves into trouble by eating more than they do normally because strenuous gym sessions leave them ravenous.

Brief, high-intensity exercise does not stimulate appetite as much, because it demands far less energy expenditure, so participants in the trial don’t suffer the same cravings.

What’s more, it appears to do something even more beneficial, according to Professor Timmons.

‘We have found that people feel their appetites are suppressed,’ he says. ‘We should have the final evidence for this next year.’

The regime should also raise people’s metabolic rates after they stop exercising, as it builds muscle — and this tissue makes metabolisms run faster. In turn, this stimulates the breakdown of fat and burns calories.

Timmons’ team also speculates that high-intensity training uses far more muscle tissue than aerobic exercise.

They say: ‘Cycling really vigorously uses not just the leg muscles, but also the upper body including arms and shoulders, so 80 per cent of the body’s muscle cells can be activated, compared to 20 to 40 per cent for walking or moderate intensity jogging or cycling.’

It will be about two years, though, before the British scientists publish their full findings as part of a Europe-wide study. In the meantime, they point out: ‘You don’t need a scientific explanation to enjoy the benefits.’

The team’s theories about short-burst exercise are increasingly supported by other research.

More at:  Is three minutes a week of exercise all you need to get fit? Scientists say ideal fitness regime involves intense bursts of activity

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