Are Roast Potatoes Cooked in Oil High in Syns? – Slimming World Syn Guide + Recipe

If you’re planning a Sunday roast, you may be wondering: are roast potatoes cooked in oil high in syns on Slimming World? Traditional roasties taste amazing when cooked in fat, but the added oil can quickly push up your daily syn allowance.

In this guide, we’ll break down the syn values of roast potatoes cooked in oil, compare popular supermarket and frozen options, and share our best recipe for low-syn Slimming World roast potatoes.

Are Roast Potatoes Cooked in Oil High in Syns?

Yes – roast potatoes cooked in oil are considered high in syns. A typical 100g portion has 5–10 syns depending on the type of oil or fat used. This is because potatoes themselves are syn-free, but the added fat from sunflower oil, goose fat, or beef dripping increases the syn value.

For example:

• Roast potatoes in sunflower oil – up to 10 syns per 100g
• Goose fat roast potatoes – around 8–9 syns per 100g
• Beef dripping roast potatoes – around 5–6 syns per 100g

That’s a big chunk of your daily syn allowance gone on just one side dish.

Why Are Roast Potatoes in Oil So High in Syns?

The problem isn’t the potatoes – it’s the fat. Cooking in oil or animal fat adds 3–5g of fat per serving, depending on how much is absorbed. Since Slimming World calculates syns based on calories from fat, these extra oils significantly raise the total syn value.

👉 Slimming World tip: To save syns, swap oil for a low-calorie cooking spray (such as Frylight) or use stock to parboil before roasting. This way you still get crispy, golden roasties without spending unnecessary syns.

Syn Values Of Roast Potatoes

Here’s a quick reference list of syn values for popular supermarket and frozen roast potatoes. Values are approximate and based on average serving sizes.

• Tesco Finest Beef Fat Roast Potatoes 800g – 7.5 syns
• Toby Carvery Beef Dripping Roast Potatoes – 5.5 syns
• Aunt Bessie’s Duck Fat Roast Potatoes 700g – 8 syns
• Tesco Crispy Roast Potatoes 450g – 13 syns
• Aunt Bessie’s Crispy & Fluffy Roasties 1.3kg – 8 syns
• Lidl Deluxe Goose Fat Roast Potatoes 1kg – 16.5 syns (per 150g)
• Aunt Bessie’s Homestyle Mini Roasties 700g – 7 syns
• Tesco Mini Roast Potatoes with Garlic Oil 500g – 5 syns
• Slimming World Roast Potatoes 1kg (Iceland) – 5 syns
• Asda Crispy Roast Potatoes 800g – 6 syns
• Aldi Four Seasons Crispy Roast Potatoes – 8 syns
• M&S Goose Fat Roasting Potatoes 450g – 9 syns
• Aldi Specially Selected Goose Fat Roast Potatoes 1kg – 9.5 syns
• Co-op Frozen Roast Potatoes 750g – 5 syns
• Morrisons Roast Potatoes 1kg – 6 syns
• Sainsbury’s Roast Potatoes 900g – 7 syns
• Asda Crisp & Fluffy Roast Potatoes 400g – 6 syns
• Tesco Finest Lemon & Thyme Roast Potatoes 400g – 7 syns

Slimming World-Friendly Roast Potatoes Recipe

Here’s a healthier, syn-friendly way to make roasties at home:

Ingredients

• 900g potatoes (Maris Piper or King Edward work best)
• Chicken or vegetable stock
• Low-calorie cooking spray
• Salt, pepper, and herbs of choice

Method

1. Peel and chop potatoes into even chunks.
2. Parboil in stock for around 5 minutes.
3. Drain and shake the potatoes in a sieve to rough up the edges.
4. Preheat oven to Gas Mark 8 / 230°C.
5. Spray with low-calorie cooking spray and season well.
6. Spread evenly on a baking tray and roast for 45–60 minutes, turning once.

✅ You’ll end up with crispy, fluffy roasties – completely syn-free if only spray oil is used.

Final Thoughts

Roast potatoes cooked in oil may taste indulgent, but at 5–10 syns per 100g, they’re not the best choice if you’re following Slimming World. Thankfully, making your own low-syn roasties at home with spray oil is simple, budget-friendly, and guilt-free.

If you’re eating out or buying frozen versions, always check the packaging or Slimming World app for the most accurate syn values.

👉 Want to keep your Sunday roast slimming-friendly? Swap roasties for syn-free Slimming World roast potatoes – you’ll save syns for dessert instead!

Frequently Asked Questions

How are syn values calculated?

Syn values are calculated using a formula based on calories, saturated fat and sugar content per serving. They’re not the same as calories — a product can be low in calories but higher in syns if it’s high in sugar or fat. Always check the official Slimming World app for the most accurate and up-to-date syn values.

Do syn values change?

Yes. When manufacturers reformulate their products, the syn value can go up or down. This is why we recommend double-checking with the Slimming World app or your consultant, especially if a product’s packaging has changed recently.

How many syns should I have per day?

Most Slimming World members work with 5 to 15 syns per day. Your consultant will advise on the right amount for you. The key is to use your syns on the things you enjoy most — whether that’s a chocolate bar, a glass of wine, or a packet of crisps.