How Many Syns In A Big Mac? Find Out Here!

Updated on 
8 May, 2022

Is A Big Mac High In Syns? Can I Have One On Slimming World?

Mcdonalds are typically a big no-no on diets, but in slimming world you can be flexible with what you eat, as long as you're tracking your syns, so how many syns does a big mac have?

Big Macs have on average have 27 syns per burger, which is nearly double the amount of your daily syn allowance, we would avoid picking Big Macs when eating foods from Mcdonald's due to their high syn count.

How Many Syns In A Big Mac?

To help you stay on track with your Mcdonald's, we've composed a short guide below, covering why big macs are so high in syns, the syn values of their burger range and some low syn burgers from other takeaway chains as well as our SW burger recipe!

Why Are Big Macs So High In Syns?

You might be shocked to learn that big macs have 27 syns a burger, these burgers get their syns due to their large size, with three bread buns rather than two, and two beef burger patties inside, hence why they are double the amount of syns than your standard.

Big macs are very unhealthy and should be avoided when trying to lose weight, one burger has up to 25g of fat which is nearly all of your recommended fat allowance for the day. Processed cheese and sauces also add in additional calories.

Syn Values Of Mcdonald's Burgers

Mcdonalds have a huge range of burgers other than their big mac with varying syn values, we've listed the rest of them down below to help you compare your options.

  • McDonald's Quarter Pounder Burger with Cheese - 26 syns.
  • McDonald's Mayo Chicken Burger - 14 syns.
  • McDonald's Double Quarter Pounder Burger with Cheese - 37.5 syns.
  • McDonald's Filet-o-Fish Burger - 16.5 syns.
  • McDonald's Chicken Big Mac Burger - 27 syns.
  • McDonald's McPlant Burger - 21.5 syns.
  • McDonald's Chicken Legend Burger with Cool Mayo - 26.5 syns.
  • McDonald's McSpicy Chicken Burger - 24 syns.
  • McDonald's Big Tasty with Bacon Burger - 42 syns.
  • McDonald's Big Tasty BBQ Burger - 38.5 syns.
  • McDonald's Homestyle Crispy Chicken Burger - 34.5 syns.
  • McDonald's Chicken Legend Burger with Hot & Spicy Mayo - 26 syns.
  • McDonald's Big Tasty Burger - 40 syns.
  • McDonald's Chicken Legend Burger with BBQ Sauce - 24 syns.
  • McDonald's Bacon Mayo Chicken Burger - 16.5 syns.
  • McDonald's Double Big Mac Burger - 40 syns.

Low Syn Burgers From Other Takeaways

Mcdonalds burgers can be very high in syns, luckily there are plenty of other food chains offering takeaway burgers, we've listed a few low syn alternatives to check out below.


  • KFC Mini Fillet Burger - 14.5 syns.
  • KFC Fillet Burger - 24 syns.
  • KFC Zinger Burger - 22.5 syns.
  • KFC Zinger Tower Burger - 30 syns.
  • KFC Fillet Tower Burger - 31 syns.
  • KFC Vegan Burger - 22.5 syns.
How Many Syns In A Big Mac?

Burger King

  • Burger King Whopper Burger - 32 syns.
  • Burger King Chicken Royale Burger - 30 syns.
  • Burger King Bacon Double Cheeseburger - 22 syns.
  • Burger King Bacon Double XL Cheeseburger - 46 syns.
  • Burger King Crispy Chicken Burger - 27 syns.
  • Burger King Vegan Royale Burger - 28.5 syns.
  • Burger King Double Whopper Burger - 44.4 syns.
  • Burger King Plant Based Whopper Burger - 28 syns.
  • Burger King Double Cheeseburger - 21 syns.
  • Burger King Cheeseburger - 14 syns.
  • Burger King Chicken Royale Bacon & Cheese Burger - 36 syns.
  • Burger King Halloumi King Burger - 32.5 syns.

Five Guys

  • Five Guys Bunless Little Hamburger - 10 syns.
  • Five Guys Little Bacon Burger - 25.5 syns.
  • Five Guys Bacon Burger - 35.5 syns.
  • Five Guys Little Hamburger - 21.5 syns.
  • Five Guys Hamburger - 31.5 syns.

Our Best Slimming World Burger Recipe

One of the best ways to find a low syn burger is by making your own at home! We've got you covered with a great low syn SW burger recipe below which is syn free and makes two burgers.


  • 250 of lean beef mince.
  • One garlic clove.
  • 1/4 of an onion.
  • Pinch of tomato paste and black pepper.


  1. Preheat your oven grill then dice up the onion and garlic, mix with the tomato paste and beef then make two patties.
  2. Grill for ten minutes on each side or until cooked and serve in wholemeal rolls as your healthy extra B.

Last Words

To conclude, Mcdonald's big macs are very high in syns, costing you nearly double your syn allowance for the day, they are also very high in fat due to their extra-large size.

How Many Syns In A Big Mac?

We would recommend avoiding big macs entirely and choosing lower syn burgers with a reduced size such as their mayo chicken burger which has 16 syns, or try making your syn free burger at home!

Jennifer is a certified nutritionist and weight loss coach with a Master's in Nutrition from Cambridge. With over 10 years experience, she shares healthy recipes and science-backed slimming tips on SheCooksSheEats to help people reach their wellness goals. Jennifer stays up-to-date by regularly attending conferences and continuing her nutrition education. She aims to provide research-backed advice to inspire balanced, happy living.
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