Tag Archive for: spot reduction

HIIT: Specific Fat Loss

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What were the results of HIIT training? The researchers found that there were reductions in overall weight as well as subcutaneous and visceral fat. What’s the difference? The fat just under the skin is subcutaneous fat; visceral fat is behind the abdominal muscles and around the internal organs and is more related to the development of cardiovascular disease and type 2 diabetes. There were no differences in the outcome variables with two exceptions:

  • Those who were in the running group lost a greater percentage of subcutaneous fat than the cycling group at 16.1% vs. 8.3%. The other difference was that positive changes in the microbiome were correlated with the loss of subcutaneous fat. Before you get too excited, the actual loss of subcutaneous fat was close to two pounds in the running group and about one pound in the cycling group. Still, ask your butcher for one pound of fat and see what it looks like. It’s a lot and probably worth the effort doing the HIIT program.
  • The other benefit was an improvement in some positive bacteria in the microbiome. It wasn’t associated with running or cycling; it was correlated with the loss of subcutaneous fat. It seems that visceral fat would show more benefit, but that wasn’t the case. Maybe someday we’ll find out why.

The obvious problem with doing a running HIIT program is that you have to be able to run—at least for 45 seconds. While my running is progressing slowly, I do intervals only while walking or riding the exercise bike. But running for 45 seconds? I can handle that.

Finally, while I was puzzled about the microbiome benefits, I also questioned why there was a difference between cycling and running when it came to the loss of subcutaneous fat. The researchers didn’t have a reason to explain it. I’ll give you my informed opinion: running integrates more of the core during the actual interval than cycling does. My hunch could be tested with sensors that detect the electrical activity of muscles, but that’s fine tuning that might not be necessary. As a scientist, I always want to know why, but that’s not important; it’s just important that it is.

We’ve seen that 30 minutes of moderate walking can prevent the loss of muscle and a HIIT running program can help lose subcutaneous fat in those who are overweight. How about getting fitter faster? Is that possible? Find out next week when we look at SIT training—and sitting does have something to do with it!

What are you prepared to do today?

        Dr. Chet

Reference: Med Sci Sports Exerc 2024 May 1;56(5):839-850.



HIIT and Fat Loss

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One of the “facts” exercise professionals will tell you is that there is no such thing as spot reduction; by that I mean you cannot target a specific area of your body, let’s say your abdominal area, and lose fat by doing a targeted exercise such as sit-ups or leg lifts. You can make the muscles underneath the skin stronger for sure, but there doesn’t seem to be any evidence that you can reduce the amount of fat in that area.

With 35 years of experience in the field, I would say that requires a qualified answer—it needs to be qualified with the word yet. There hasn’t been a study that proves that you can reduce fat in a specific area yet. Is it theoretically possible? Yes, I think it is. The problem is this: who would do the high quantity of exercise focused on one area long enough per workout session to do themselves any good? It may be that we’ve approached it all wrong by focusing on resistance exercise. Let’s take a look at another study that compared high-intensity interval training (HIIT) on a cycle ergometer versus a treadmill.

Researchers began with two questions. Is there any difference in the fat mass in specific areas of the body after training using a cycle ergometer (an exercise bike that measures the energy output of the cyclist) or a treadmill? In addition to that, is there any change in beneficial microbes in the microbiome after training?

Let’s take a look at what they did. Researchers recruited 16 men with a mean age of 54 and initial BMI of 29.9. After assessing initial fitness level, body fat, and body-fat distribution using the DEXA scan, and taking an initial stool sample for analysis of the microbiome, the subjects were randomly assigned to the bike or the treadmill. To make sure that there were no significant changes in diet, the subjects were required to maintain their typical diet and do seven-day diet records periodically during the study.

Think of this as intervals for the everyday exerciser. The HIIT bike program required them to do ten intervals for 45 seconds each at 80–85% of the maximal heart rate (MHR), and then a 90-second active recovery, or a HIIT running program which were nine intervals for 45 seconds at 80–85% of MHR and again with 90 seconds of recovery between intervals. They were to do this exercise under supervision three times per week for 12 weeks. The goal was to have all exercisers use the same number of calories during the workouts, whether cycling or running. The subjects were then retested to examine the differences if there were any. What did they find? I’ll tell you on Saturday.

What are you prepared to do today?

        Dr. Chet

Med Sci Sports Exerc 2024 May 1;56(5):839-850.

Spot Reduction? Maybe

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Researchers collected data from four prior studies that put a group of sedentary overweight and obese men and women on a walking program. To determine the distribution of muscle, fat, and bone, they took MRIs of their entire body. That gave the researchers not only the amount of muscle and fat mass, but exactly where that muscle and fat were located.

Once researchers assessed the fitness level of these subjects, they developed an exercise prescription for them that had them exercise at 60% to 75% of their maximal aerobic capacity for 30 minutes a session, five days a week, for six months. Their heart rates were monitored throughout the exercise session to make sure that they did not exercise above those levels; that also allowed subjects to increase the speed or grade of the treadmill as they got fitter. The subjects used a food log to track all the food they ate.

Results

Did the subjects lose some weight? Yes. Even though they were trying to maintain what they ate, they were using more calories in exercise than they had been, so they did lose some weight—in this case, just a little over two pounds in the exercising group. The controls actually gained about half a pound in the six-month study.

Now to the good stuff. The results of the MRI showed that there were definitely regional differences in skeletal mass and fat mass. As was expected, the exercising muscles, primarily the hips, thighs, and legs, saw maintenance of the skeletal muscle mass but a decrease in the fat mass. In the upper part of the body, there was a slight decrease in muscle mass in the arms and upper torso with a very slight decrease in fat mass compared to controls.

The Bottom Line

So what does this all mean? First, because the mean age was around 55, maintaining muscle mass is critical—this is the time of life when age-related muscle loss starts to occur.

Second, if this were confirmed in several clinical trials, it would mean that there should be a focus on weight training or aerobic training that utilizes the entire body. Elliptical trainers and recumbent cross trainers come to mind as something that would use both the arms and the legs, so that may be part of the solution. And from personal experience, I can say that dance classes can have a similar effect.

In order to preserve muscle mass, exercising all your muscles is important; 60 to 75% of maximal fitness would be classified as moderate exercise. That means you don’t have to kill yourself in order to obtain the benefits of regular exercise to your cardiovascular system. Add to that some weight training a few days a week, and you have your own prescription for sustaining muscle mass and maybe losing just a little bit of fat mass along the way. But what if I told you that you could increase the loss of fat mass, especially in your abdominal region, by changing up the intensity of your workouts for a few weeks? Next week’s Memos will look at that research.

What are you prepared to do today?

        Dr. Chet

Reference: MSSE. 2024. 56(5):776-782.

Is Spot Reduction Possible?

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One of the questions that I’ve thought about over the years is what happens to the skeletal muscle and fat mass in non-exercising parts of the body. If you’re a runner or a walker, what happens to your upper body? What happens to your lower body? Do you retain or even increase the muscles in your thighs and calves? Do you lose fat from your legs? How about your upper body? Do you maintain the muscle mass that you had, or do you lose some? What about the fat mass? Lose or gain?

When I was a graduate student, I ran the body composition laboratory. Over my years in the lab, I underwater weighed probably 5,000 people, from five-year-olds to 90-year-olds, from those who were underweight to morbidly obese, from tiny little gymnasts to a Big 10 hockey team. While underwater weighing was the gold standard at the time, it used some assumptions about the distribution of skeletal muscle, bones, and fat mass that weren’t as precise as they should be. These days, state-of-the-art is dual X-ray absorptiometry, which is called DEXA for short. But that doesn’t give us a precise analysis of body composition to answer those questions either.

We now have that technology in magnetic resonance imaging. Using MRI can begin to give us the answer to those questions about muscle and fat mass. Can you get rid of that stubborn belly fat? We finally may have some answers, and I’ll tell you about the latest research on Saturday.

Don’t forget to send me your list of vegetables and fruits you ate over the weekend—and remember the ketchup!

What are you prepared to do today?

        Dr. Chet