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GLP-1: when you eat less

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GLP-1 Side effects?

Our team supports you every step of the way: helping you understand your needs, identify the nutrients to prioritize and find the supplements that fit your new routine.

Reduced appetite, constipation, new eating habits… GLP-1 treatments act mainly on appetite and satiety, and can bring their share of changes to daily life. When you eat smaller amounts, it can become harder to meet certain nutritional needs. Every bite counts.

Study 1 · Diagnosed deficiencies (medical records)

Nutritional deficiencies observed in patients on GLP-1

Recent research has looked at diagnosed deficiencies and dietary intake in people using these treatments.

An observational study published in 2025 analyzed diagnoses of nutritional deficiencies and related complications in 461,382 adults after starting GLP-1 treatment.

These results reflect diagnoses recorded during the follow-up periods, not necessarily deficiencies that appeared exactly at month six or month twelve.

Sources: Butsch et al., PMC 2025 (n = 461,382 patients) · Urbina et al., Clinical Obesity 2026 (n = 480,825 adults)

% of patients diagnosed with a deficiency

6 months12 months

Zinc6.0 %3.0 %
Vitamin B128.0 %4.0 %
Calcium9.0 %5.0 %
Magnesium11.0 %6.0 %
Iron14.0 %8.0 %
Protein17.0 %10.0 %
Vitamin D13.6 %7.5 %
At least one deficiency22.4 %12.7 %

Muscle loss Protein + Creatine

Why does protein matter when you eat less?

Fewer meals also means less protein, and your body may draw on your muscles to make up the difference. It’s one of the first effects of a reduced appetite: muscle mass declines, and with it, strength and everyday energy. The simplest fix: include a protein source at every meal, even a small one. The goal isn’t to eat more, but to choose better.

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Your body renews its proteins constantly: muscles, skin, hair, enzymes, immune defences. When you eat less, your total intake often drops without you noticing, because portions shrink across the board.

Muscle is the reserve most sensitive to this shortfall. When energy and protein drop together, part of the weight lost can come from muscle mass, not just fat mass. This is even more true after 50.

How you spread it out matters as much as how much. Aiming for a serving of protein at every meal helps your body use it better. If your appetite is low, more concentrated foods (Greek yogurt, eggs, tofu, protein powder) get you there without big plates.

To choose your protein, look for a complete protein that’s easy to digest and concentrated in a small volume. Whey and soy check these boxes; so do plant blends that combine several sources, like pea and rice. Collagen, on the other hand, isn’t a complete protein and shouldn’t be your only source.

Beyond the type, look at the amount of protein per serving, the ingredient list and your digestive tolerance. Our advisors can help you compare options based on your tastes, your digestion and your budget.

What exactly is creatine?

Creatine is a substance naturally present in the body, mainly in the muscles. It’s also found in certain foods such as meat and fish.

Its role is to help rapidly renew the energy your muscles use during short, intense efforts.

When you lift weights, climb stairs quickly or do an exercise that requires power, your muscles rely in part on an energy system that creatine contributes to.

How can creatine support your muscles?

When combined with resistance training, it can help support performance and promote training adaptations. That’s what makes the combination worthwhile.

How do you add creatine to your routine?

Creatine monohydrate is the most studied form. In studies, a daily dose of 3 to 5 g is commonly used to maintain high muscle stores.

It can be mixed into water, a smoothie or a protein shake. Taking it consistently generally matters more than the exact timing.

One thing to know: creatine can increase the amount of water held in your muscles. This can affect the number on the scale without necessarily reflecting an increase in fat mass.

Key figures

1.2–1.6g

of protein per kg, per day

Min. 30g

of protein per meal

25–50g

in a protein shake, 1 to 2 per day

3–5g

of creatine monohydrate per day

These figures are for information only. Your needs may vary: talk to a healthcare professional.

Key points

  • Include a protein source at every meal, even a small one.
  • Start your plate with the protein when your appetite is limited.
  • Choose a complete protein: whey, casein, beef, soy or a plant blend.
  • Check the amount of protein per serving on the label.
  • A protein snack can make up for a skipped meal.

Under treatment or medical follow-up? Check your needs with your healthcare professional.

Sources

  • Alverstone Health (2026). GLP-1 Nutrition Protocol.
  • GLP-1 Nutrition Lab (2026).
  • Momentous / Frontiers (2025).
  • OneDayMD Protocol (2026).
  • Butsch et al. (2025). PMC.

Hydration

How do you stay well hydrated when you eat less?

When you eat less, you often drink less too, because part of your water comes from food. Your sense of thirst can also fade with age or when your appetite changes. The simplest approach: drink at set times rather than waiting until you’re thirsty. Water remains the best everyday drink.

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Water carries nutrients, helps regulate body temperature and plays a role in digestion. Part of your intake comes from what you eat: soups, fruit, vegetables, yogurt. When portions shrink, that intake drops too.

The signs of insufficient hydration are subtle: fatigue, headaches, dark urine, constipation. That’s why a routine works better than instinct.

Keep a bottle within reach, pair a glass of water with every meal and snack, and lean on water-rich foods. Herbal tea, sparkling water or a slice of citrus work just as well.

What about electrolytes?

Electrolytes, such as sodium, potassium and magnesium, help your body hold on to the water you drink and use it where it’s needed. They also support normal muscle and nerve function. Since a good share comes from food, they can drop when you eat less, especially with nausea, vomiting or diarrhea.

An electrolyte supplement, as a powder or a tablet dissolved in water, can help round out your hydration, for example after exercise, in hot weather or on a day when you’ve eaten little. Choose a low-sugar formula and check with your healthcare professional if you have heart, kidney or blood pressure concerns.

Key points

  • Drink a glass of water with every meal and snack.
  • Don’t wait until you’re thirsty to drink.
  • Keep a bottle in sight: on your desk, in your bag.
  • Lean on water-rich foods: soups, fruit, vegetables.
  • Think electrolytes after exercise, in hot weather or when you’ve eaten little.
  • Check the colour of your urine: pale is a good sign.

Under treatment or medical follow-up? Check your needs with your healthcare professional.

Key figures

2.7L

of total water per day, women

3.7L

of total water per day, men

≈ 20%

of water comes from food

≈ 80%

of water comes from drinks

300–500mg

of sodium per electrolyte serving

1 serving

of electrolytes during or even before exercise

These figures are for information only. Your needs may vary: talk to a healthcare professional.

Sources

  • Institute of Medicine (2004). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academies Press.
  • Health Canada (2019). Canada’s Food Guide — Make water your drink of choice.

Digestive health

How do you keep enough fibre when portions shrink?

Fibre is often the first thing to drop when you eat less, because it comes from bulky foods. Vegetables, fruit, whole grains and legumes fill you up fast, so they get left aside. Yet fibre supports bowel regularity and contributes to satiety. The key: choose more fibre-dense options rather than big portions, and increase them gradually while drinking enough.

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There are two main types of fibre. Soluble fibre (oats, legumes, some fruits) slows digestion. Insoluble fibre (whole grains, vegetable skins) adds bulk and promotes regularity.

When appetite drops, we keep the easy foods and drop the vegetables and whole grains. The result: fibre intake falls faster than everything else, and constipation becomes more common.

The winning strategy is density: chia or ground flaxseed in yogurt, lentils in a soup, whole-grain bread.

Fibre, prebiotics, probiotics: what’s the difference?

A fibre supplement, as a powder to mix into water or a smoothie, helps close the gap when portions are small. It supports bowel regularity and should be introduced gradually, with a large glass of water.

Prebiotics are specific fibres that feed the good bacteria in your gut. Probiotics are those live good bacteria, found in yogurt, kefir or capsules. The two work together to support the balance of your gut flora, which is often disrupted when your diet changes.

A supplement doesn’t replace food, but it can make things easier during this period. A Popeye’s advisor can help you choose the formula that fits your routine.

Key points

  • Choose whole grains: oats, barley, whole-wheat bread and pasta.
  • Add a spoonful of seeds (chia, ground flax) to one meal a day.
  • Include legumes a few times a week.
  • Increase your fibre gradually to avoid discomfort.
  • Drink more when you add fibre.
  • Consider prebiotics and probiotics to support your gut flora.

Under treatment or medical follow-up? Check your needs with your healthcare professional.

Key figures

25g

of fibre per day, women

38g

of fibre per day, men

5–10g

of supplemental fibre per day

2h

between fibre and medication

5–10g

of psyllium (prebiotic) per day

10–30 bn

CFU of probiotics per day, with a meal

These figures are for information only. Your needs may vary: talk to a healthcare professional.

Sources

  • Institute of Medicine (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Values adopted by Health Canada.
  • Health Canada (2019). Canada’s Food Guide.
  • Alverstone Health (2026). GLP-1 Nutrition Protocol.
  • GLP-1 Nutrition Lab (2026).
  • Momentous / Frontiers (2025).
  • OneDayMD Protocol (2026).
  • Butsch et al. (2025). PMC.

Vitamins

Which vitamins should you watch when you eat less?

Eating less can also mean unintentionally cutting back on vitamins. The ones to watch first are vitamin D, vitamin B12 and the other B vitamins. Your needs don’t decrease when your appetite drops, and some increase with age. An advisor can help you see whether a supplement makes sense for you.

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Vitamin D contributes to bone health and muscle function. In Canada, the sun isn’t enough to produce adequate vitamin D for much of the year, and few foods contain it naturally.

Why D3 with K2?

Vitamin D3 (cholecalciferol) is the preferred supplement form. Paired with vitamin K2 (MK-7 form), it helps direct calcium to the bones. Together, they support bone density and immunity. Take them with a meal that contains some fat for better absorption.

Vitamin B12

Vitamin B12 is found almost exclusively in animal foods. When you eat less meat, eggs or dairy, your intake drops, and fatigue or brain fog can set in. As a supplement, methylcobalamin as a sublingual tablet (under the tongue) is an easy form to take in the morning.

What about a multivitamin?

When portions stay small for several weeks, a multivitamin acts as a safety net: it helps cover your basic needs in a single dose. It doesn’t replace food and doesn’t always provide enough vitamin D3 or B12 on its own. An advisor can help you see whether a targeted supplement would also be useful.

Key points

  • Aim for nutrient-dense foods: fatty fish, eggs, dairy or fortified drinks.
  • Choose vitamin D3 and take it with K2, during a meal.
  • Eat few animal products? Pay attention to B12.
  • A multivitamin can fill a gap, not replace meals.
  • Avoid stacking several supplements without advice.

Under treatment or medical follow-up? Check your needs with your healthcare professional.

Key figures

2,000–4,000 IU

of vitamin D3 per day

100–200µg

of vitamin K2 (MK-7) per day

500–1,000µg

of supplemental B12 per day

1 dose / day

of multivitamin, with a meal

These figures are for information only. Your needs may vary: talk to a healthcare professional.

Sources

  • Alverstone Health (2026). GLP-1 Nutrition Protocol.
  • GLP-1 Nutrition Lab (2026).
  • Momentous / Frontiers (2025).
  • OneDayMD Protocol (2026).
  • Butsch et al. (2025). PMC.

Minerals

Which minerals should you watch when you eat less?

Minerals are among the first nutrients to drop when portions shrink. Calcium, iron, magnesium and zinc come mainly from dairy, meat, legumes, nuts and whole grains. Your needs stay the same when your appetite drops. An advisor can help you see whether a supplement makes sense for you.

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Calcium supports bone health, along with vitamin D. As a supplement, calcium citrate is taken in two doses of 500 to 600 mg, at least 2 hours apart from iron.

Iron helps carry oxygen in the blood. Needs are higher for women before menopause. Plant-based iron is better absorbed with a source of vitamin C.

Magnesium contributes to muscle and nerve function. Glycinate or malate forms are preferred, ideally in the evening. Zinc supports the immune system and wound healing.

What about omega-3s?

The omega-3s EPA and DHA, found mainly in fatty fish, support cardiovascular health, help reduce inflammation and help preserve lean mass. When you eat less fish, a concentrated fish oil can help. Take it with a meal that contains fat and check the label: aim for at least 500 mg of EPA+DHA per capsule.

Key points

  • Keep a daily source of calcium: dairy, fortified drinks, tofu.
  • Take calcium and iron at least 2 hours apart.
  • Pair plant-based iron with a food rich in vitamin C.
  • Choose magnesium glycinate or malate, in the evening.
  • Omega-3: aim for at least 500 mg of EPA+DHA per capsule.

Under treatment or medical follow-up? Check your needs with your healthcare professional.

Key figures

1,000–1,200mg

of calcium per day

300–400mg

of magnesium per day

8–11mg

of zinc per day, while maintaining a balanced copper intake.

1,000–2,000mg

of omega-3 EPA+DHA per day

These figures are for information only. Your needs may vary: talk to a healthcare professional.

Sources

  • Alverstone Health (2026). GLP-1 Nutrition Protocol.
  • GLP-1 Nutrition Lab (2026).
  • Momentous / Frontiers (2025).
  • OneDayMD Protocol (2026).
  • Butsch et al. (2025). PMC.

Everyday

What should you actually eat tomorrow morning?

Start with a small portion that combines protein and fibre, like Greek yogurt with berries and oats. You can top up later with a snack if a full meal doesn’t go down.

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Is it better to eat three meals or several small portions?

There’s no single right formula. When appetite is low, smaller meals and planned snacks can help spread your intake over the day. Choose a routine that lets you eat enough.

How do you make a small meal more nourishing?

Add a protein source, a fibre source and, depending on your needs, a more energy-dense food like nuts or avocado. The idea is to improve nutritional quality without excessively increasing volume.

Study 2 · Measured dietary intake (food diaries)

And on the plate? Nutrient intake that sometimes falls short.

A second study published in 2025 in Frontiers in Nutrition analyzed the dietary intake of 69 adults on GLP-1 treatment.

Researchers observed average intakes below certain nutritional recommendations, notably for fibre, vitamin D and several minerals.

Source: Investigating nutrient intake during use of glucagon-like peptide-1 receptor agonist: a cross-sectional study (2025)

Average measured daily intake

Protein

77.3g

Fibre

14.5g

Calcium

863mg

Magnesium

266mg

Vitamin D

4µg

Iron

12.1mg

Potassium

2,186mg

Vitamin C

51mg

Averages observed in the study sample. A measured intake alone does not indicate a confirmed deficiency.

When you eat less, every food choice counts more toward meeting your nutritional needs.

Key takeaways

Eating less, without missing the essentials

Research shows that some people on GLP-1 have diagnosed deficiencies or insufficient intake of essential nutrients.

These findings highlight the importance of keeping a varied diet, paying attention to your nutrient intake and getting support suited to your needs.

These studies do not show that GLP-1 treatments systematically cause deficiencies. The data presented are observational and nutritional needs vary from person to person. Insufficient dietary intake does not necessarily mean a confirmed deficiency.

The essentials

If you’re eating much less than before, three things matter more than anything else: protein, water and fibre.

01 How much protein and how to get there with a small appetite 02 What to actually eat tomorrow morning 03 Which protein to choose

Need a hand?

We’re with you every step of the way

Our advisors help you adapt your choices to your appetite, your tastes and your budget, in store or online. And if you’re under treatment, they’ll encourage you to talk it over with your healthcare professional.

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