You’re making tuna sandwiches wrong: the 2-tablespoon swap that saves 200 calories, adds protein

The much-loved tuna sandwich earns its place in lunchboxes for price, speed and protein. Yet many of us still fight a dry filling or drown it in heavy mayo. A small switch reshapes texture, trims calories and keeps the rich mouthfeel you expect.

A cheap classic that needs a little help

Tinned tuna is lean, briny and punchy. It also dries out fast once drained. That’s why so many households reach for mayonnaise. The result tastes indulgent, but it adds a hefty energy cost for very little extra nutrition. Swap the binder, not the fish, and the sandwich changes character without losing comfort.

Two tablespoons of thick Greek yoghurt deliver the creamy feel of mayo with fewer calories and extra protein.

The simple swap that changes everything

Use Greek yoghurt instead of mayonnaise to bind tuna. The texture stays lush, the flavour gains a gentle tang, and the numbers look kinder. Many home cooks use three to four tablespoons of mayo per tin; trading that for two tablespoons of Greek yoghurt can shave roughly 180–260 kcal off a single sandwich, depending on brands and fat levels.

Values vary by brand, but the direction of travel is consistent: fewer calories, less fat, more protein, and a brighter taste.

How to build a better tuna sandwich in five minutes

• Drain one tin of tuna packed in water and flake it with a fork.
• Add 2 tbsp Greek yoghurt. Use 5% for richness or 2% for a leaner finish.
• Season with salt and black pepper. Stir until just combined.
• Brighten with 1 tsp lemon juice and 1 tsp Dijon mustard if you like.
• Spread on wholegrain bread, add crisp lettuce or sliced cucumber, and serve.

For a richer mouthfeel without mayo, whisk 1 tsp extra-virgin olive oil into the yoghurt before mixing with tuna.

What yoghurt works best

Thickness matters. Strained, full-bodied Greek yoghurt clings to the fish and resists sogginess. A 5% fat tub gives a rounder, creamier finish. A 2% pot trims calories further yet still binds well. Non-fat versions taste sharper and can turn chalky, so balance with a little olive oil or an extra squeeze of lemon if you go very low fat. If you avoid dairy, a Greek-style coconut or soy yoghurt with minimal sugar achieves a similar texture, though the flavour profile changes slightly.

Does it taste like mayonnaise

Not exactly. It tastes fresher. Greek yoghurt brings a subtle tang that wakes up tuna’s savoury notes. The filling feels lighter yet still indulgent, especially if you choose a mid-fat yoghurt. People who prefer a classic mayo tone can add a pinch of garlic powder and a few drops of olive oil to round the edges.

Smart add-ins that lift flavour

This base welcomes bold accents. Keep the list short to avoid drowning the fish.

• Acid: lemon juice or a splash of white wine vinegar for brightness.
• Heat: a dash of hot sauce or a pinch of Aleppo pepper.
• Herbs: dill, parsley or chives for freshness.
• Salty pops: capers or finely chopped cornichons.
• Crunch: celery, spring onion or cucumber diced small.
• Richness: 1 tsp extra-virgin olive oil if you want a silkier finish.

Keep the ratio tidy: 1 tin tuna, 2 tbsp Greek yoghurt, 2 teaspoons of flavourings, and one crisp element for texture.

Nutrition, cost and practicality

A standard tin of tuna in spring water offers around 22–25g protein. Two tablespoons of Greek yoghurt add another 4–5g. That extra protein helps satiety during long afternoons at work. Wholegrain bread contributes fibre, which slows digestion and steadies energy. Compared with a mayo-laden version, the yoghurt blend usually reduces saturated fat and sodium.

Cost stays friendly. A tin of tuna and a few spoonfuls of yoghurt likely sit well under the price of a high-street sandwich. The yoghurt tub stretches across several lunches without much effort. Leftover filling keeps in the fridge for up to two days in a covered container. Stir before spreading, as the yoghurt may firm up.

Buying and safety tips

• Choose tuna packed in water for cleaner flavour and easier seasoning control.
• Check the yoghurt label for protein (aim for 8–10g per 100g) and moderate fat for body.
• If you prefer tuna in oil, drain it well, then reduce or skip any added olive oil.
• Keep the filling chilled below 5°C and assemble sandwiches close to eating time.
• Pregnant people and young children can prioritise skipjack tuna for lower mercury exposure.

Ways to tailor the sandwich to your goals

For more protein, add a sliced egg or choose skyr, which is extra high in protein and behaves like Greek yoghurt. To reduce energy further, serve the filling in a wholegrain wrap or on seeded rye. Those watching salt can use no-salt-added tuna and season with lemon and herbs rather than extra salt.

Craving comfort? Toast the bread for crunch, then add a thin slice of cheddar and grill briefly to melt. The yoghurt base won’t split under gentle heat, so the filling stays creamy. For a packed lunch, store the filling and bread separately and combine just before eating to preserve texture.

Small changes compound: swapping mayo for Greek yoghurt can save well over 1,000 kcal across a working week of sandwiches.

Beyond sandwiches

The same Greek yoghurt trick upgrades potato salad, pasta salad and baked potatoes. It binds salmon flakes, rotisserie chicken or chickpeas with ease. Keep the method constant: two tablespoons of yoghurt per portion, a little acid for brightness, and something crunchy for contrast. You keep the creamy comfort while nudging the meal in a leaner, higher-protein direction.

If lactose is a concern, lactose-free Greek yoghurt offers the same texture. For a fully plant-based route, choose a thick unsweetened soy or coconut yoghurt and adjust seasoning with lemon, mustard and olive oil to match the balance you like. The principle remains the same: build creaminess, add tang, and let the tuna shine.