Big, meaty portobello mushrooms make the perfect edible bowl, and stuffed with a savoury filling of spinach, tomato, feta and a crisp topping, they become a genuinely satisfying low-calorie dinner. At around 300 calories with 16g of protein, these stuffed mushrooms deliver a deep, savoury, almost meaty satisfaction that makes them a favourite even with committed carnivores. Low-carb, quick and delicious.
A quick word first: I am not a doctor or a dietitian, just someone who lived this. None of these foods or supplements are medication, and if you are on a GLP-1, check anything new with your GP or pharmacist. Right, let us get to it.
For more evening ideas, see my high-protein dinner ideas, and for meat-free protein, how much protein per day.
Why portobello mushrooms are a low-carb hero
These giant mushrooms are one of the best low-calorie building blocks in the kitchen.
A savoury, meaty base for almost no calories. Portobello mushrooms are big, satisfying and packed with umami, so they give a deep, savoury base for barely any calories or carbs.
The filling brings protein. Feta, a little cheese and the savoury filling push the protein to a respectable 16g, making this more substantial than it looks.
Naturally low-carb and quick. No pastry, no bread, no faff — just a stuffed mushroom baked until golden, ready in under half an hour.
How mushrooms win over the meat-eaters
I have mentioned before that I am not vegetarian, but I actively seek out meat-free dinners that genuinely satisfy, and mushrooms are my secret weapon for winning over anyone sceptical about a meal without meat. The reason is umami — that deep, savoury, mouth-filling taste that we most associate with meat. Mushrooms, and particularly big, meaty portobellos, are absolutely loaded with it. When you eat a well-cooked, well-seasoned stuffed portobello, your palate gets much of the same savoury satisfaction it would from a piece of meat, which is why even committed carnivores tend to enjoy a dish like this rather than feeling short-changed.
This is genuinely useful knowledge on a GLP-1. Meat-free dinners bring more fibre, more variety and a lower food bill, but they only work long-term if they actually satisfy you, and a sad, watery vegetable dish will not. Building your meat-free meals around deeply savoury, umami-rich ingredients like mushrooms is the key to making them satisfying enough that you choose them for their own sake, not as a grudging compromise. Beyond mushrooms, you can build umami with tomatoes, cheese, a splash of soy sauce, miso, or slow-cooked onions. But mushrooms are the star, and a big stuffed portobello is one of the most satisfying meat-free dinners you can put in front of someone. Serve these to a mushroom-sceptic cooked properly — golden, savoury and generously filled — and you may well change their mind. They are proof that meat-free does not have to mean missing out.
The macros that matter
Here is roughly what one serving gives you. Treat these as a guide rather than gospel, since it depends on your exact ingredients and portions:
| Approx per serving | Amount |
|---|---|
| Calories | ~300 kcal |
| Protein | 16g |
| Carbohydrate | 18g |
| Fat | 16g |
| Fibre | 6g |
The protein figure is the one I watch on a GLP-1. As a rough guide I aim for somewhere around 1.2 to 1.6g of protein per kilo of body weight across the day to protect muscle while losing fat, and I judge every meal by how much of that it contributes. I log meals like this in Cronometer (it is free) so I know I am actually hitting my targets rather than hoping. The first time I tracked properly I realised I was eating far less protein than I thought, so if you have never done it, give it two weeks.
What you need (serves 1)
- 4 large portobello mushrooms, stalks removed
- 2 big handfuls of spinach, wilted and chopped
- 4 cherry tomatoes, chopped
- 1 clove garlic, crushed
- 60g feta, crumbled
- 2 tbsp grated cheese (cheddar or parmesan)
- 2 tbsp wholemeal breadcrumbs
- 1 tsp olive oil
- Fresh parsley, salt and black pepper
- To serve: a big green salad
How to make it
- Heat the oven to 190C (fan 170C). Place the mushrooms gill-side up on a baking tray and brush lightly with olive oil.
- Mix the wilted spinach, chopped tomatoes, garlic, crumbled feta, parsley, salt and pepper for the filling.
- Spoon the filling into the mushroom caps, pressing it in gently.
- Mix the grated cheese and breadcrumbs and scatter over the top for a crisp finish.
- Bake for 20–25 minutes until the mushrooms are tender and the topping is golden and crisp.
- Scatter with fresh parsley and serve with a big green salad.
Adjusting it to your goals
At 16g this is a light dinner, so on a hungrier day:
Boost the protein. Add cooked lentils, quinoa or extra cheese to the filling, or serve with a side of chicken or eggs.
Serve with a substantial side. A quinoa or bean salad alongside adds protein and fibre.
Add more veg to the filling. Peppers, courgette or extra tomato bulk it out. See fibre on GLP-1.
Cooking mushrooms so they do not go watery
The one pitfall with cooking mushrooms, and stuffed mushrooms especially, is that they release a lot of water, and if you are not careful you end up with a soggy, watery dish sitting in a pool of liquid. There are a few simple ways to avoid this. First, do not wash mushrooms by soaking them in water, as they act like sponges and soak it up — instead, wipe them clean with a damp cloth or give them a very quick rinse and pat dry. Second, when you are baking stuffed mushrooms, roasting them gill-side up, as in this recipe, lets any liquid evaporate rather than pooling. Some cooks pre-roast the empty caps for a few minutes first to drive off excess moisture before filling them, which is worth doing if your mushrooms are particularly large or wet. Third, a crisp topping of breadcrumbs and cheese, as here, helps absorb moisture and gives a lovely contrast in texture. And if you are cooking mushrooms in a pan rather than the oven, the rule from the mushroom stroganoff applies — use a decent heat and do not overcrowd, so the water cooks off and they brown rather than stew. Get these basics right and your stuffed mushrooms will be tender and savoury with a crisp top, rather than swimming in liquid. It is a small thing, but it is the difference between a mushroom dish that satisfies and one that disappoints, and once you know the tricks it is easy to get right every time.
Prep the filling, bake fresh
You can make the filling and prep the mushroom caps ahead, then stuff and bake them fresh when you want dinner, which makes these a quick weeknight option. They also keep for a day or two once cooked and reheat well, making a nice next-day high-protein lunch with a salad. A light, satisfying part of my meal prep ideas for Mounjaro.
How it fits a full day of eating
At 16g of protein these are a lighter dinner, so I make sure the rest of my day carries more protein — a solid high-protein breakfasts and high-protein lunch. The feta and cheese give a respectable protein base for a vegetable dish.
Bulk the filling with lentils or quinoa, or serve with a protein side, for a more substantial meal, and a protein shake covers any gap. Being very low-carb and low-calorie, these suit an evening where I have had plenty earlier in the day. As always, it is the daily total that counts — my complete GLP-1 guide explains how I balance it.
No appetite today?
Light, soft and savoury, a stuffed mushroom is fairly gentle on a low-appetite evening, and even one delivers protein and veg without being heavy. When cooking feels like too much, though, a simpler option or HelloFresh bringing a ready meal may suit better. More in what to eat with no appetite.
Supplements that pair well
As a plant-forward dinner it is low in omega-3, so I add Super Omega-3 EPA. Mushrooms exposed to light can provide some vitamin D, but I still top up with Vitamin D3 + K2 in winter, and a daily Super Supplemental covers general gaps. The free Lily & Loaf lifestyle analysis matches a routine to your goals.
Frequently asked questions
Are stuffed mushrooms filling enough for dinner?
As a light, low-calorie dinner they are surprisingly satisfying thanks to the meaty mushrooms and savoury filling. For a hungrier day, add lentils or quinoa to the filling, or serve with a protein side or a substantial salad.
How do I stop them going watery?
Do not soak the mushrooms when cleaning them, bake them gill-side up so liquid evaporates, and add a breadcrumb topping to absorb moisture. Pre-roasting the empty caps for a few minutes helps with very large ones.
Can I make them vegan?
Yes — swap the feta and cheese for plant-based versions or use nutritional yeast, and check your breadcrumbs. The mushroom, spinach and tomato base is naturally vegan and very savoury.
What is the best mushroom to use?
Large portobello or field mushrooms are ideal — they are big enough to stuff, hold their shape, and have a deep, meaty, savoury flavour. Smaller mushrooms work as a starter but portobellos make a proper main.
What should I serve with them?
A big green salad keeps it light and low-carb, or add a quinoa or bean salad, or a side of chicken or eggs, for a more substantial, higher-protein meal.
The bottom line
Stuffed portobello mushrooms are a meaty-tasting, satisfying vegetarian dinner that wins over even the carnivores — deep, savoury umami and 16g of protein for just 300 calories, naturally low-carb. Building meat-free meals around umami-rich ingredients like mushrooms is the secret to making them genuinely satisfying rather than a compromise. Bulk the filling with lentils, and master the trick to non-watery mushrooms. To match your supplements to a plant-forward routine, the free Lily & Loaf lifestyle analysis is a quick, no-pressure check.
The tools I lean on
If you are putting a GLP-1 routine together, this is the order I would do it in, free tools first:
- Track a fortnight of food in Cronometer so you can see your real protein and calories.
- Take the free Lily & Loaf lifestyle analysis to find the supplements actually worth buying.
- Start an Audible trial for something to listen to while you cook or walk.
- Keep HelloFresh on standby for the weeks cooking from scratch just is not happening.
- Batch-cook and freeze portions in a set of freezer-safe containers so there is always a healthy dinner a few minutes away.
A bit about me
I am Alan Spicer. I lost around seven stone on Mounjaro and filmed the whole thing, warts and all, on my YouTube channel. Simple, protein-first dinners like this were a real part of how I held onto muscle and kept the weight off.
This article shares my personal experience and general information only. It is not medical advice. Food and supplements support a balanced diet and healthy lifestyle and do not replace it or any treatment prescribed by your doctor. Speak to your GP or pharmacist before making changes, especially while on a GLP-1 medication. Nutrition figures are approximate and will vary with the exact ingredients and brands you use.
Inspired by the kind of fresh, wholefood dinners in the Lily & Loaf evening meals collection. This is my own version, written from my own kitchen.
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