Ozempic, GLP-1, and Weight Loss: A Nutritionist’s No-Nonsense Breakdown

Celebs swear by it, TikTok can’t stop talking about it, and one of the top female athletes has taken to promoting it: here’s what GLP-1s really mean for your health.

GLP-1s are the not-so-best-kept secret dieting tool of the moment. When Serena Williams – yes, one of the greatest athletes of all time – admitted to using them (while her husband Alexis Ohanian is also investing in telehealth company Ro and she is a paid spokesperson for weight-loss meds), the internet was divided. How come a top athlete feels the need to partake in this culture? Should we all be reassessing? What does this mean for the already growing culture of Ozempic use in our everyday? 

Add this to the growing list of A-listers, influencers, and TikTok wellness gurus who’ve jumped on board (and aren’t willing to admit it), and suddenly these little injections aren’t just meds, they’re a full-on pop culture phenomenon.

Originally reserved for managing type 2 diabetes, drugs like Ozempic, Wegovy, and Mounjaro have rebranded themselves as the hottest accessory in modern dieting culture. They’re changing the way people eat, how they see their bodies, and even how they approach exercise. But here’s the catch: with all the celebrity buzz and viral chatter, it can be hard to separate facts from hype.

That’s why we tapped our nutritional lifestyle expert, Marta Decarli, to break it all down, from the science to the myths, and what GLP-1s really mean for your health and food intake.

How do GLP-1 medications affect appetite and nutrient intake?

Marta Decarli: GLP-1 receptor agonists (e.g., semaglutide, tirzepatide) act on the brain’s appetite-regulating circuits and slow stomach emptying. People feel full sooner, have fewer cravings, and often eat smaller portions—so overall calorie intake drops. That’s the primary way they support weight loss.

What lifestyle changes do GLP-1 meds cause?

MD: Common, practical shifts I see:

• Smaller meals, earlier fullness, and sometimes a natural preference for lighter foods.

• Slower eating pace (because gastric emptying is slower). Some people reduce alcohol and ultra-processed snacks simply because they’re less appealing.

• These effects stem from centrally reduced appetite and delayed gastric emptying. 

  Are there specific foods or nutrients to prioritise while on a GLP-1?

  MD: Yes—prioritise protein, produce, and plants:

• Protein at each meal: eggs, Greek-style yoghurt/dairy alternatives, tofu/tempeh, pulses, fish, lean meats, or high-protein grains. This helps maintain muscle and curb hunger.

• High-fibre plants for gut health and fullness: vegetables, fruit, beans, lentils, whole grains, nuts, seeds.

• Fluids & electrolytes: small, frequent sips if nausea is an issue.

• Gentle-on-the-stomach choices (especially during dose increases): broths, soups, smoothies, tender grains, and modest fat portions to limit GI symptoms. Expert guidance supports smaller, more frequent meals.

  Do these meds change how the body absorbs vitamins or protein?

  MD: They slow the rate food leaves the stomach and moves through the gut, which can delay the appearance of nutrients in the blood after a meal. That’s not the same as causing true malabsorption. Most reported deficiencies likely reflect eating less overall (and sometimes nausea) rather than the drugs blocking absorption. Evidence confirms slowed gastric and small-bowel transit but does not show consistent protein malabsorption.

  What are effective strategies for preventing muscle loss associated with decreased appetite?

  MD: As follows:

• Anchor protein: aim ~1.2–1.6 g/kg/day (higher if very active), split across 3–4 meals (≈0.25 g/kg/meal).

• Lift 2–4×/week: resistance training is the strongest non-drug signal to preserve lean mass during energy deficit.

• Quality calories: don’t “survive on bites.” Add easy calories to small portions (olive oil, avocado, nut butters, milk/fortified plant milks).

• Plan the first 2–3 bites to be protein-rich (e.g., yoghurt + whey, tofu, eggs), then add veg and starch.

  How can we still fuel our bodies whilst eating much less?

• MD: Shrink the meal, not the nutrition: use nutrient-dense foods (eggs, oily fish, legumes, dairy/fortified alternatives, nuts/seeds).

• Smoothies/soups are clutch if solids feel heavy—blend fruit/veg with Greek-style yogurt or protein powder and oats.

• Front-load protein and batch-cook small, freezer-friendly portions to avoid skipping meals.

• Micro-meals (½ sandwich + yoghurt; small bean bowl; cottage cheese + fruit) beat long gaps with no intake. Expert consensus supports smaller, more frequent meals for GI tolerance.

  What role does protein play in supporting healthy weight loss on GLP-1s?

  MD: Protein helps you lose more fat and less muscle, keeps you fuller, and has a higher thermic effect (it’s “costly” to digest). During weight loss—drug-assisted or not—intakes around 1.2–1.6 g/kg/day (sometimes up to ~2.0 g/kg for heavy training) are consistently linked with better lean-mass retention.

  How can you transition into sustainable eating habits if you stop the medication?

• MD: Keep the structure that worked: protein-centred meals, plenty of fibre, planned snacks.

• Expect appetite to return—pre-commit to balanced plates and a consistent meal rhythm rather than “white-knuckling” hunger.

• Continue resistance training to protect resting energy expenditure.

• Monitor, don’t obsess: track weight, strength, and how clothes fit over 8–12 weeks, adjusting portions—not cutting food groups.

• Longer-term data show weight regain is common if old habits return; skills-based nutrition and training are your safety net. (Body-composition substudies show greater fat-than-lean loss on GLP-1s, reinforcing the value of protein + training both during and after.

  How does exercise fit in—any nutrition tweaks to support strength training on a GLP-1?

• MD: Lift first, then eat (or have a small protein-carb snack pre-session if you feel flat).

• Target ~0.25–0.4 g/kg protein within a couple of hours after training, and hit your daily total. Add some carbs for better performance/recovery.

• If nausea reduces intake, try liquid nutrition (chocolate milk or a simple shake) post-workout.

• Well-designed programs mixing resistance + aerobic exercise help preserve muscle and fitness while on GLP-1s. 

  Should meal timing change since digestion can slow on these meds?

  MD: Usually, yes—smaller, more frequent meals tend to feel better than large ones. Many people do well with 3 modest meals + 1–2 small protein-rich snacks. Avoid very high-fat, heavy meals near injections or dose escalations, which can aggravate GI symptoms.

  What’s your take on Serena Williams, one of the world’s top athletes, taking a GLP-1 now? How might this affect her as a sportsperson?

  MD: GLP-1 medications have become the “magic pill” many people with weight struggles have been hoping for—by blunting appetite, they make it far easier to reduce food intake. I can understand Serena’s endorsement. As women, and especially as mothers, there’s constant scrutiny around how we look—so even for someone at her level of achievement, that pressure doesn’t disappear.

  From a physiological perspective, these medications could make fueling for high-level sport more challenging, simply because hunger cues are dampened and digestion slows. That means she’d need to be very intentional about protein intake, muscle recovery, and meeting energy demands. What I admire most is that she has been open about it despite knowing the debate it would spark—it shows how complex the conversation around weight, performance, and body image really is.