Just how effective is exercise for the prevention of getting fat (or fatter) vs. transforming a fat body into a lean body? Research has surprising results.
Exercise can be extremely useful for keeping weight off once you’ve lost it, while also improving overall health and self-confidence.
But exercise just by itself is not likely to lead to major weight loss, says the research. This doesn’t mean don’t include it in your weight loss efforts. It’s still extremely vital.
One reason workouts may not produce the expected results is that exercise can increase appetite.
But be careful with this expectation, because a workout session has also been known to suppress appetite — depending on the type of activity.
Also, that “increase” in appetite can sometimes be due to feeling deserving of some extra food “because I really did well in the gym.” The amount of food eaten after the exercise then doesn’t equal the amount of hunger actually felt.
There’s another factor, too. People may subconsciously become less active during the rest of the day after exercising, as in, “I worked my butt off at the gym; it’s okay to be a couch potato all evening.”
This can encourage overeating as well as burn fewer calories than you normally would have.
The body can also adapt to regular activity. Over time, it may become more efficient at performing the same exercise, meaning fewer calories are burned during that activity.
The workaround for this, though, is to employ progression in the workout, such as using a faster speed, a higher pedal resistance, taking a tougher class or lifting heavier weight.
Exercise needs to be progressive, not stagnant.
Exercise May Be Better for Keeping Weight Off
While exercise isn’t necessarily the biggest factor in initial weight loss, it appears to be much more important for preventing weight regain.
One study involving more than 1,100 people found that physical activity had little impact on how much weight participants initially lost.
However, people who remained more physically active after losing weight were much more likely to keep it off.
How Exercise Can Help Prevent Weight Regain
One possible explanation involves resting energy expenditure, or the number of calories the body burns while at rest. This is called basal metabolic rate (BMR).
After weight loss, the body generally burns fewer calories at rest than it did before.
This is because it takes less energy to sustain a lighter body. The BMRs of very overweight clients of mine were always higher than were the BMRs of thinner clients — as recorded by a metabolic cart.
You breathe into a mouthpiece or mask while the machine measures oxygen consumption and carbon dioxide production.
Those measurements are used to calculate resting metabolic rate (RMR), which is often used as an estimate of BMR.
A 300 pound person may have a BMR of around 3,000, while a 130 pound person may have a BMR of around 1,300.
But remember: Two people of the same height, age, sex and weight may have different BMRs because one has much more muscle mass than the other. Body composition plays a role in energy expenditure at rest.
That said, an exercise routine increases overall daily energy expenditure, which can help counter some of that decline in BMR that results from having a lighter body.
When striving to lose weight, you must make every effort to prevent muscle loss. Strength training is crucial. Muscle is the body’s metabolic furnace.
Exercise and Fat Burning
Physical activity can also affect how efficiently the body uses fat for energy.
After losing weight, the body may become less effective at burning fat.
More intense exercise can improve fat oxidation and metabolic flexibility, which is the body’s ability to switch between using carbohydrates and fat for fuel.
That flexibility can be helpful when calorie intake is lower or after significant weight loss.
Exercise also improves insulin sensitivity. Better insulin sensitivity means the body doesn’t need as much insulin to manage blood sugar.
Higher insulin levels can encourage fat storage and make it harder for the body to break down stored fat, so improving insulin sensitivity can provide another advantage.
Exercise can also help regulate appetite and blood sugar.
