Medication or Fasting? A Scientific Perspective on Modern Obesity Treatment

By: Tetsuya Tanimoto, MD

Chairman of Accessible Railway Medical Services Tetsuikai Medical Corporation

Director of Navitas Clinic Kawasaki

In the ever-evolving world of metabolic health management, we stand at a peculiar, almost mystical crossroads. On one side, a line-up of cutting-edge pharmaceuticals, the stars of which are GLP-1 receptor agonists, have appeared, almost from thin air. These drugs—sleek, precise, and modern—promise a life free from constant hunger and the wild spikes of blood sugar that torment so many. They’re like something out of science fiction but wrapped in a prescription label. On the other side, we find an ancient practice, an old friend of humanity: fasting. It’s not high-tech, and it requires no prescription, just patience and maybe a little discipline. Fasting taps into the rhythms encoded in us from eons ago, a kind of genetic echo of our ancestors’ lives. It’s no wonder it’s making a comeback, embraced by everyone from Silicon Valley’s tech gurus to regular folks like me. So here I am, a doctor and a person who’s dabbled in both methods, at this strange juncture, wondering: Which path, if either, leads to health?

The Rise of GLP-1 Receptor Agonists

Let’s start with GLP-1 receptor agonists. They’re the wunderkinder of the pharmaceutical world, the kind of treatment that waltzes into the clinic and rewrites the rules. These medications mimic glucagon-like peptide-1, a hormone produced in the intestine that, to put it simply, keeps appetite in check and blood sugar levels smooth [1]. With just the right mix of effects, GLP-1 agonists reduce hunger pangs, slow down gastric emptying, and boost insulin sensitivity [2]. It’s almost elegant, as if the hormone itself knows to say, “Hey, you’re full,” or “Time to balance that sugar spike.”

The results from clinical studies are impressive. Take the STEP-1 trial, for example. Published in the prestigious New England Journal of Medicine, it showed that patients on semaglutide—one of these GLP-1s—lost an average of 14.9% of their body weight over 68 weeks. This wasn’t a “try it for a weekend and feel a little lighter” type of result. This was transformative weight loss, with placebo patients losing just 2.4% by comparison [3]. And then there’s the SUSTAIN-6 trial, which showed that GLP-1s can even deliver cardiovascular benefits [4]. For patients who once struggled with energy, who got winded walking up stairs, it was like rediscovering their own bodies. You could say they’d found a magic potion—in a small vial, of course, with a prescription label.

The Evolutionary Perspective on Fasting

But while GLP-1 receptor agonists are a marvel of modern medicine, fasting is a gift of ancient biology. Picture our ancestors—they didn’t exactly eat three square meals a day, nor did they snack on demand. They ate only when they managed to hunt, gather, or forage something edible. The body had to adapt to these cycles of feast and famine, developing a kind of metabolic flexibility. This flexibility might make you picture a yogi of internal chemistry, one who can gracefully switch between different fuel sources depending on what’s available [5]. No synthetic hormones, just the body’s natural ability to adapt.

Fasting is like turning off the engine for a bit to give it a tune-up. The magic kicks in after about 12 hours when the body shifts from burning glucose to stored fat, creating ketones as an alternative energy source [7]. There’s also the process of autophagy—a sort of cellular cleanup. Think of it as spring cleaning for your cells, sweeping away damaged parts that don’t quite belong anymore [8]. Research even suggests that autophagy may play a role in slowing down aging and shielding against age-related diseases [9]. Fasting, then, isn’t just about eating less; it’s about reconnecting with our body’s reset button and finding those ancient rhythms.

The Science Behind Intermittent Fasting

In recent years, scientists have delved into intermittent fasting with a vigor worthy of any mystery. A comprehensive review in the New England Journal of Medicine detailed fasting’s benefits, from improved glucose regulation to reduced inflammation [11]. Another study in Cell Metabolism tested early time-restricted feeding (similar to my own approach) and found impressive gains in insulin sensitivity, blood pressure, and oxidative stress markers—without any required weight loss for benefits [12].

In Nature Metabolism, researchers found that fasting encourages the body to produce β-hydroxybutyrate, a molecule with anti-aging properties that helps cells combat inflammation and stress [13]. A meta-analysis in Clinical Nutrition revealed that intermittent fasting’s weight loss results are comparable to continuous calorie restriction but with added perks, such as lower insulin levels and a more efficient fat metabolism [14]. Intermittent fasting isn’t just another health fad. It’s a modern revival of an ancient practice, validated and illuminated by science.

My Personal Journey with Intermittent Fasting

Like many, the COVID-19 pandemic tossed my routines around like leaves in the wind, leaving me with a few more pounds and a desire for some stability. This journey led me to try intermittent fasting—not just as a doctor but as a person, seeking something practical, something that felt right.

My chosen plan was time-restricted eating: a neat, eight-hour window from 7 a.m. to 3 p.m., perfectly mirroring our circadian rhythms. You’d think this simple shift wouldn’t make much difference, but research indicates that eating earlier aligns better with our natural metabolic rhythms, leading to better health and even weight loss [15]. The results surprised me: ten kilograms down, energy up, mental clarity sharpened. Intermittent fasting didn’t just change my waistline; it changed my relationship with food. Freed from cravings, I felt as if I’d stepped off a hamster wheel. I could finally breathe.

Practical Considerations and Limitations

Of course, no health practice is without its challenges. Fasting has its quirks. While it might sound like the holy grail, it’s not ideal for everyone. Fasting can lead to low blood pressure, a problem if you already struggle with hypotension or take medications that amplify this effect [17]. Dehydration can also be an issue, especially for those who dive into extended fasting without adequate water [18].

Hormones add another layer of complexity. For women, fasting can disrupt hormonal balance, particularly in those with specific endocrine conditions. For anyone considering fasting, it’s crucial to consider your medical history, lifestyle, and even medication schedules [19]. Fasting isn’t a magic pill; it’s a tool. And, like any tool, it has to be handled with care. While it may be a powerful method for some, others may need to proceed cautiously or explore different paths.

The Future of Obesity Treatment: An Integrated Approach

Where does this leave us? The future of obesity treatment likely lies not in a choice between medicine and fasting, but in understanding how they complement each other, merging the best of modern science with the wisdom of ancient practices. GLP-1 receptor agonists offer a powerful tool, while intermittent fasting taps into evolutionary rhythms that speak to the body’s resilient core. Each approach opens unique pathways to health; together, they might forge a truly comprehensive solution.

The question, then, isn’t which path to choose but how to combine these approaches thoughtfully. Imagine your health as a song with intricate harmonies—sometimes the medication is the melody, and fasting is the subtle rhythm that carries it along. Each patient is a unique symphony, shaped by individual biology, lifestyle, and personal goals.

Ultimately, the goal of obesity treatment in the 21st century isn’t merely about shedding pounds. It’s about living fully, energetically, and with joy. And maybe, just maybe, somewhere in the blend of GLP-1 receptor agonists, time-restricted eating, and our personal journeys, we’ll find a deeper understanding not only of health but of ourselves.

References

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2.      Davies M, Færch L, Jeppesen OK, et al. Semaglutide 2.4 mg once a week in adults with overweight or obesity. Lancet. 2021;397(10278):971-984. doi:10.1016/S0140-6736(21)00213-0.

3.      Rubino DM, Greenway FL, Khalid U, et al. Effect of Weekly Subcutaneous Semaglutide vs Daily Liraglutide on Weight Loss in Adults with Overweight or Obesity: The STEP 8 Randomized Clinical Trial. JAMA. 2022;327(2):138-150. doi:10.1001/jama.2021.23619.

4.      Wadden TA, Bailey TS, Billings LK, et al. Effect of Subcutaneous Semaglutide vs Placebo as an Adjunct to Intensive Behavioral Therapy on Body Weight in Adults With Overweight or Obesity. JAMA. 2021;325(14):1403-1413. doi:10.1001/jama.2021.1831.

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