Regular movement and exercise are essential for health. Our Paleolithic ancestors had a different word for exercise: “life.” Naturally, they spent a lot of time outdoors in the sun, walking, hunting, gathering, and performing various other physical orientation tasks. They had no concept of this as “exercise” or “exercise.” It was just life.

But while exercise contributes to health in a number of different ways, it is sometimes not very effective for weight loss . Or, more specifically, low-intensity “cardio,” which is the way most people exercise, is not effective for weight loss.

Why Cardio Doesn’t Work For Weight Loss

How could this be? There are three main reasons:

  • The calorie burn during exercise is generally small.
  • People who exercise more also tend to eat more (which negates the weight-regulating effect of exercise).
  • Increasing specific periods of exercise can make people more sedentary otherwise.

An example of the first reason was a study that followed women over a period of one year found that to lose one kilogram (2.2 pounds) of fat, they had to exercise for an average of 77 hours. That’s a long time on the treadmill just to lose 2 pounds!

In an example of the second reason, one study found that people who exercise tend to eat more afterward and tend to crave high-calorie foods. The title of this study says it all: “Acute compensatory eating after exercise is associated with an implicit hedonic craving for food.”

In the third reason, one study assigned 34 overweight and obese women to an exercise program for 8 weeks. Fat loss at the end of the study averaged 0.0 kg. Not very impressive. But the researchers noticed that some women lost weight, while others actually gained. What was the difference?

In women who did not lose weight, the increase in specific periods of exercise corresponded with a decrease in total energy expenditure. Translation: They were more likely to be addicted to television when they weren’t exercising, nullifying the calorie-burning effect of their workouts.

Low intensity exercise is ineffective for losing fat

If you’re still not convinced, the Cochrane group conducted a review of 43 individual studies on exercise for weight loss. The duration of the study ranged from 3 to 12 months and the exercise sessions lasted on average 45 minutes with a frequency of 3-5 times per week. The results? On average, the additional weight loss from exercise averaged about 1 kg (2.2 pounds). Assuming you exercised for 45 minutes 4 times a week for 6 months, that means they had to exercise 69 hours to lose that 1 kg.

The purpose of this rather long introduction is simply to point out that low intensity “cardiovascular” exercise is spectacularly ineffective for weight loss. But that doesn’t mean that all types of exercise aren’t effective.

High intensity intermittent training (HIIT)

HIIT is a type of exercise performed in short bursts (intervals) of high intensity. Several studies have been conducted comparing HIIT to low intensity steady-state or “chronic fall” exercise, and HIIT has been shown to be superior on almost all significant markers.

In this study, one group was assigned to “chronic cardio” while the other was assigned to 8-second sprint intervals. After 15 weeks, the researchers concluded:

Both exercise groups demonstrated a significant improvement (P less than 0.05) in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat, and fasting plasma insulin levels.

A couple of studies conducted at McMaster University found that ” 6 minutes of hard exercise once a week could be as effective as one hour of daily moderate activity,” according to the June 6, 2005 CNN article that reports about the study.

The study itself was published in the Journal of Applied Physiology and revealed that HIIT resulted in unique changes in skeletal muscle and endurance capacity that were previously believed to require hours of exercise each week.

High-density exercise superior to cardio to prevent diabetes

A follow-up study confirmed the results. Although the more conventional resistance exercise group spent 97.5 percent more time engaged in exercise, both groups of subjects improved to the same degree. The group that exercised 97.5 percent more received no additional benefit from doing so.

Considering the wear and tear and increased risk of injury associated with much more exercise, there is no point doing “chronic cardio” when you can receive the same benefits with a fraction of the time and risk of doing HIIT.

The Cochrane study also found that high intensity exercise was superior to “chronic cardio . ” In particular, the researchers found that high-intensity exercise led to a greater decrease in fasting blood glucose levels than low-intensity exercise.

Why high intensity exercise is better for burning fat and losing weight

In his excellent book on high intensity strength training, Body By Science, Dr. Doug McGuff explains that high intensity training is superior to chronic cardio because it produces a greater stimulus and therefore more effectively flushes the muscles. muscles and the liver, glucose. This stimulus can last for several days with HIIT, rather than a few hours with low intensity training.

HIIT also activates hormone-sensitive lipase (HSL), which mobilizes fatty acids for energy use. This means that during HIIT, both glucose and fatty acids will be burned, leading to further fat loss and restoration of insulin sensitivity. That could help protect against diabetes and metabolic syndrome.

High Intensity Strength Training: Best of All?

Both high intensity running or cycling sprints and high intensity strength training are effective. But high-intensity strength training is probably a better option for most, simply because the wear and tear and risk of injury are less, especially if the strength training is done with weight machines.

By Dr. Eric Jackson

Dr. Eric Jackson provides primary Internal Medicine care for men and women and treats patients with bone and mineral diseases, diabetes, heart conditions, and other chronic illnesses.He is a Washington University Bone Health Program physician and is a certified Bone Densitometrist. Dr. Avery is consistently recognized in "The Best Doctors in America" list.

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