Health Management with GLP-1 Drugs? The Latest Research Reveals the Risk of Reduced Physical Activity

Health Management with GLP-1 Drugs? The Latest Research Reveals the Risk of Reduced Physical Activity

Even if weight is lost with "slimming drugs," does the step count not increase? The next challenge of the GLP-1 boom: "lack of exercise"

GLP-1-based medications, which are gaining global attention as obesity treatments, are facing an unexpected challenge. Many people believe that losing weight through medication will make the body lighter, naturally increasing the amount of walking and exercise. However, research presented at the annual meeting of the Endocrine Society, "ENDO 2026," held in Chicago in June 2026, challenges this intuition.

According to the research, individuals with obesity who started using GLP-1-based medications experienced a decrease in both daily step count and moderate-to-vigorous physical activity (MVPA) time after beginning the medication. The subjects were adults participating in the U.S. National Institutes of Health's "All of Us Research Program," with linked electronic health records and Fitbit activity data. Out of 1,950 people prescribed GLP-1-based medications, 753 with sufficient Fitbit data were analyzed.

The results are clear. The average daily step count decreased from about 5,047 steps to 4,487 steps, a reduction of approximately 560 steps. MVPA time also decreased from about 28 minutes to 22 minutes per day. Contrary to the expectation that weight loss would naturally lead to increased activity, at least in this data, the equation "weight loss = increased activity" was not confirmed.

Of course, it is too early to conclude from this study alone that "GLP-1 drugs make people lazy." The study is a retrospective observational study and does not prove that the medication directly reduced exercise levels. Many subjects were women, with an average age of 52.7 years, and many suffered from joint and muscle pain. There are numerous factors that could affect activity levels, such as pre-existing health conditions, pain, living environment, work, changes in food intake, side effects, and fatigue during weight loss.

Nevertheless, the issue raised by this study is significant. GLP-1-based medications, which utilize hormones involved in appetite and blood sugar regulation, are rapidly spreading as drugs that aid in weight loss. Semaglutide, liraglutide, dulaglutide, and tirzepatide are now discussed in the context of diabetes treatment and obesity management. The image of "losing weight with medication" has already permeated the general public both in Japan and abroad.

However, losing weight and becoming healthy are not the same. Weight loss can include not only fat but also muscle mass reduction. Especially with rapid weight loss, protecting muscle becomes crucial. Muscles are not just about appearance; they are deeply involved in blood sugar processing, posture maintenance, fall prevention, basal metabolism, and independence in daily life. Even if the scale shows a lower number, if muscle is lost and activity levels decrease, there are other risks to long-term health.

In this study, the decline in activity levels was particularly pronounced among men and those with joint and muscle pain. This is a very realistic result. Even if weight is reduced to some extent, knee or back pain may not disappear immediately. If side effects such as nausea, stomach discomfort, fatigue, and decreased food intake occur, there may be days when exercise is out of the question. Furthermore, if the medication suppresses appetite, there is a possibility of insufficient energy and protein intake, leading to increased fatigue.

On the other hand, psychological factors cannot be ignored. For those who have repeatedly failed at dieting, GLP-1 drugs can become a "finally found means." As appetite decreases and weight begins to drop, it may appear that results are being achieved without exercise. Therefore, it is not surprising if some people think, "The medication is enough for now," or "I can exercise after losing more weight." The greater the effect of the medication, the more likely it is that lifestyle improvements will be postponed.

Reactions on social media also reflect this complexity well.

In the comments section of news articles, a harsh view that "relying on medication may not change lifestyle habits" is prominent. Some criticisms strongly link obesity to personal negligence. These reactions indicate that social prejudices surrounding obesity and weight loss drugs are still deeply rooted. Medically, obesity cannot be explained solely by a lack of willpower; it is a chronic health issue involving genetics, metabolism, environment, sleep, stress, medication, and socioeconomic conditions. Nevertheless, on social media, there is a tendency to simplify the issue to "people using medication are not making an effort."

Meanwhile, voices closer to those involved are more conflicted. Some who have been prescribed GLP-1 drugs express anxiety, wondering if they should start after seeing news like this. In communities of those already taking the medication, experiences such as "feeling too fatigued to exercise," "struggling with intense exercise due to nausea," and "losing too much appetite to have energy" are shared. This is a reality that cannot be dismissed as mere "dislike of exercise."

 

In GLP-1-related communities on Reddit, discussions such as "Is exercise necessary while on medication?" and "Can weight be lost without exercise?" are repeated. Some say that weight can decrease without exercise, while others emphasize that exercise, especially strength training, is essential to preserve muscle. Additionally, some feel that starting exercise slowed their weight loss, but this could be due to temporary changes in muscle mass and water content affecting the scale. In other words, on social media, perspectives of "people wanting to lose weight" and "people wanting to maintain a healthy body composition" often clash.

This is the most important aspect of diet reporting in the GLP-1 era. While medication may lower weight, if success is measured solely by one number—weight—then essential indicators like muscle mass, physical strength, cardiovascular function, blood sugar management, and quality of life become less visible. In the short term, "how many kilos lost" is highlighted, but in the long term, questions like "how to maintain the lost weight," "how to preserve muscle," and "how to sustain life after stopping the medication" arise.

GLP-1 drugs are intended to be used in combination with dietary management and increased physical activity. In the U.S., obesity treatment drug descriptions also mention low-calorie diets and increased physical activity. In other words, the medication is positioned as an aid to improve lifestyle habits, not a substitute. This study suggests that this principle is not always naturally implemented in real life.

So, how should people using GLP-1 drugs think about it?

First, the necessary mindset is to "create small habits of movement while the medication is effective." There is no need to start intense exercise suddenly. It is unrealistic to demand long hours of training every day from those experiencing nausea, fatigue, or joint pain. Instead, starting with small exercises that can be incorporated into daily life, such as walking for five minutes after meals, taking the stairs instead of the elevator once, breaking up sitting time every hour, or doing light squats and wall push-ups, is more sustainable.

Next, strength training is crucial. While aerobic exercise benefits cardiovascular function and blood sugar management, exercises that stress muscles are necessary to preserve muscle mass. Even without going to a gym, bodyweight exercises, resistance bands, light dumbbells, and stair climbing can be sufficient. Especially for middle-aged and elderly individuals, preventing muscle loss during weight loss is directly linked to quality of life thereafter.

Additionally, support from doctors, registered dietitians, physical therapists, and trainers is important. It is not enough to simply prescribe GLP-1 drugs; specific support is needed, such as assessing whether the person experiences severe nausea, whether they are getting enough protein, which exercises are safe if they have joint pain, and how to record steps and strength training. The "intervention in physical activity parallel to pharmacotherapy" emphasized by the researchers refers to precisely this kind of support.

Judging by the reactions on social media, public debate still tends to lean towards a dichotomy of "medication or effort." However, reality is neither. GLP-1 drugs can be a powerful option for those who have struggled with weight management. On the other hand, medication alone does not solve all health issues. If the medication reduces appetite, what kind of diet should be chosen during that time? If weight begins to drop, how should the lighter body be moved? If side effects prevent activity, how should adjustments be made with healthcare providers? All of this is part of the treatment.

The message from this study is not a simple "GLP-1 drugs are dangerous and should be stopped." On the contrary, to maximize the benefits of the medication, exercise needs to be designed as "part of the treatment," not just an "add-on."

Weight loss is indeed a significant achievement. However, healthy weight loss is not just about the numbers decreasing; it also means being able to walk longer distances, climb stairs more easily, maintain muscle strength, improve blood sugar and blood pressure, and gradually gain more freedom in daily life. In the upcoming era where GLP-1 drugs are spreading, the real question is not just "how much weight was lost."

"Can you remain in a body capable of movement after losing weight?"

Answering this question is becoming the next challenge for the GLP-1 boom.


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