GLP-1 drugs like Ozempic and Wegovy have become impossible to ignore. Searches for "Ozempic" now outpace searches for "keto." If you're following a low-carb diet and wondering how these medications compare — or whether you should consider them — here's an honest look at what both actually do.

How each one works

Keto cuts carbohydrates to around 20–50 g per day, which shifts your body from burning glucose to burning fat for fuel. Appetite tends to drop naturally once you're in ketosis — partly because fat and protein are more filling, partly because ketones themselves appear to suppress hunger signals.

GLP-1 drugs (semaglutide in Ozempic and Wegovy, tirzepatide in Mounjaro and Zepbound) mimic a hormone your gut releases after eating. They slow digestion, reduce appetite, and help regulate blood sugar — so you eat less without having to consciously restrict anything.

Both approaches reduce how much you eat. They just get there differently.

Weight loss results

GLP-1 drugs produce larger and faster weight loss in clinical trials — typically 15–20% of body weight over a year or more, compared to 5–10% typically seen with dietary changes alone (GLP-1 evidence review). If speed and magnitude of weight loss are the priority, the medications have an edge in the data.

What happens to your muscles

This is where keto holds a meaningful advantage.

With GLP-1 medications, research suggests that 25–40% of total weight lost can come from lean mass — muscle — rather than fat. That's a real concern, especially for older adults where muscle loss accelerates naturally.

A study presented at ENDO 2026 (the Endocrine Society's annual meeting, June 2026) found something else: people taking GLP-1 drugs became significantly less physically active after starting the medication. Researchers analysed Fitbit data from the NIH All of Us programme and found daily step counts and exercise levels dropped — even as the number on the scale went down (ScienceDaily, Healthline).

Less movement plus muscle loss is a combination worth taking seriously.

Ketogenic diets, by comparison, have been shown to preserve lean mass during weight loss, particularly when protein intake is kept adequate (StatPearls). And the diet gives you no reason to move less.

Side effects

GLP-1 drugs cause gastrointestinal symptoms — nausea, vomiting, diarrhoea — in 10–50% of users. Rarer but more serious risks include pancreatitis. Most side effects are manageable, but they're common enough to matter.

Keto's main side effect is the keto flu in the first week or two — fatigue, headaches, and muscle cramps as your body adapts. It's temporary and manageable (keto flu: why it happens and how to feel better).

Cost and access

GLP-1 medications are expensive — typically hundreds of dollars per month — and require a prescription and ongoing medical supervision. They're out of reach for many people without insurance coverage.

Keto costs whatever your food costs. No prescription, no clinic visits, no supply chain.

What happens when you stop

Both approaches have a sustainability problem, but it shows up differently.

People who stop GLP-1 medications typically regain most of the weight within a year. The drug suppresses appetite; without it, appetite returns.

People who stop keto also regain weight if they return to old eating habits. But the skills — reading labels, knowing what's in food, understanding how carbs affect hunger — stay with you in a way that stopping a medication doesn't replicate.

So which should you choose?

There's no universal answer, and this isn't a decision to make based on an article.

GLP-1 drugs may be appropriate if you have significant weight to lose, a medical condition like type 2 diabetes that responds well to them, and access to a doctor who can supervise.

Keto may suit you if you want a sustainable, affordable approach you control fully, don't want to depend on a medication long-term, and are willing to put in the initial adaptation period.

Some people use both — a ketogenic diet can help reduce the muscle loss and inactivity risk that comes with GLP-1 use. That's worth discussing with your doctor if you're considering the combination.

An honest note

GLP-1 drugs are genuinely impressive medications. This article isn't arguing against them. It's pointing out that keto offers things the drugs don't — muscle preservation, cost, autonomy — and that some recently identified downsides of GLP-1 use (reduced physical activity, lean mass loss) are areas where diet-based approaches have an advantage.

Talk to your doctor before starting either, especially if you take medication for diabetes or heart disease.

New to keto? Start with What is the ketogenic diet?

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