How Many Syns Are in Custard? Your Guide to Slimming World Desserts

December 1, 2025 •

4 min read

According to the Slimming World blog, a simple homemade custard recipe can be as low as 2.5 Syns per serving. Knowing exactly how many syns are in custard is crucial for staying on track with your weight loss journey, as the values vary significantly depending on the type and brand.

Quick Summary

Syn values for custard differ based on whether it is homemade, a packet mix, or ready-made. Options like fat-free yogurt-based recipes offer very low Syns, while most shop-bought versions and traditional recipes carry higher values.

Key Points

Syns vary significantly: The Syn value for custard depends on whether it's homemade, ready-made, or from a powder.
Homemade is often lowest: Making custard from scratch with skimmed milk (using Healthy Extra allowance) and sweetener can result in a very low-Syn dessert, sometimes as low as 0.5-2.5 Syns per serving.
Ready-made options exist: Some ready-made alternatives, like Alpro vanilla custard pots, are relatively low in Syns (1 Syn per 125g pot).
Always check labels: Ready-made custards vary greatly, so always check the product's nutrition information and use the official Syn calculator or app.
Low-Syn alternatives: Warming fat-free vanilla yogurt or adding custard flavouring to Greek yogurt are easy, low-Syn substitutes.
Custard powder isn't free: Remember to Syn both the custard powder and any milk or sugar added when making it from a mix.

Demystifying Custard Syn Values

For those following the Slimming World plan, understanding the Syn value of a favourite treat like custard is essential. The Syn count isn't fixed; it changes dramatically depending on whether you are making it from scratch, using a powder mix, or opting for a ready-made pot. This guide will break down the numbers and offer smart, low-Syn alternatives so you can still enjoy this classic comfort food without derailing your weight loss goals.

Homemade Custard: Syns and Savings

Making custard at home gives you complete control over the ingredients, which is key to managing Syns. Standard recipes can be high in sugar and fat, but with some clever substitutions, you can create a delicious dessert for a fraction of the Syns.

Slimming World Egg Custard: A recipe featured on the official Slimming World blog makes a 2.5 Syn serving by using skimmed milk (part of a Healthy Extra allowance or Synned separately) and sweetener instead of sugar.
Fat-Free Yogurt Based Custard: A creative user-submitted recipe on Facebook suggests a 1 Syn egg custard made with beaten eggs, a Muller Light vanilla or custard flavoured yogurt, sweetener, and nutmeg. A very low-Syn, creamy homemade custard using fat-free natural yogurt and semi-skimmed milk can come in at just 1/2 Syn per serving.

Ready-Made Custard: A Convenient Breakdown

While ready-made custard pots offer convenience, their Syn values can add up quickly. It's vital to check the specific product and size, as values vary significantly between brands and sizes.

Alpro Vanilla Custard Alternative: According to many Slimming World community posts, a 125g pot of Alpro vanilla custard is around 1 Syn. This makes it a popular and creamy alternative for a low-Syn treat.
Ambrosia Light Custard: A 120g pot of Ambrosia Light is reported to be 4.5 Syns.
Sainsbury's 'Be Good to Yourself' Fresh Custard: This option is noted as 3 Syns per 100g.
Standard Ready-Made Custards: Regular full-fat, ready-to-serve custards are typically much higher in Syns due to sugar and fat content. For example, a standard Tesco ready-to-serve custard is approximately 3 Syns per 100g.

Custard Powder Syns

Custard powder itself has a Syn value, which must be added to the Syns from the milk used to make it. The final Syn count depends on the brand of powder and the type of milk you choose (e.g., skimmed, semi-skimmed, or part of your Healthy Extra 'A' allowance).

Example Calculation:

Custard Powder: A typical level tablespoon of custard powder (before mixing) has a Syn value. For example, two and a half teaspoons of Vanilla Custard Powder contain roughly 36.4 calories. Using the 20 calories per Syn calculation, this would be around 1.8 Syns just for the powder.
Milk: The milk used will add to the total Syns. If you use your Healthy Extra 'A' allowance, the milk might be free, but anything beyond that must be Synned.

Custard Syns Comparison Table

To help you make an informed choice, here is a quick comparison of different custard options based on common serving sizes.


Custard Type	Approx. Syns (per serving)	Key Ingredients	Notes
Homemade SW Egg Custard	2.5	Eggs, skimmed milk (Healthy Extra 'A' or Syns), sweetener	Based on official SW blog recipe.
Homemade Quark/Yogurt Custard	1	Quark, low-fat custard, advocaat (optional)	Recipe variation reported on Facebook.
Homemade Low-Fat Custard	0.5	Fat-free yogurt, eggs, semi-skimmed milk (Healthy Extra 'A' or Syns)	Recipe from a Slimming World friendly website.
Alpro Vanilla Custard	1	Alpro vanilla custard alternative	Based on user reports for 125g pot.
Ambrosia Light Custard	4.5	Ready-made custard	Based on user reports for 120g pot.
Sainsbury's 'Be Good to Yourself' Fresh Custard	3	Ready-made fresh custard	User report for 100g serving.
Standard Custard Powder	Varies	Powder + milk (Syns)	Depends on quantity and milk choice.

How to Make a Low-Syn Custard at Home

Creating a delicious and creamy custard at home can be a rewarding way to manage your Syns. Here is a simple outline for a low-fat custard recipe:

Put your milk allowance (skimmed milk from Healthy Extra A) into a pan and warm gently.
In a separate bowl, whisk together egg yolks, cornflour, vanilla extract, and a sweetener of your choice.
Slowly whisk the warm milk into the egg mixture to temper it.
Return the mixture to the saucepan and heat gently, whisking constantly until it thickens to your desired consistency. Serve warm or chilled.

Low-Syn Custard Alternatives

If you're not in the mood for cooking, there are still ways to enjoy a creamy, custard-like texture.

Warmed Vanilla Yogurt: Gently warming a pot of low-fat or fat-free vanilla yogurt can create a lovely, custard-like sauce. Muller Light vanilla yogurt can be used for a 1 Syn alternative in some recipes.
Alpro Vanilla Custard Alternative: As noted earlier, the small pots of Alpro vanilla custard are a great ready-made option at just 1 Syn per pot.
Custard Flavouring: Adding a few drops of custard flavouring to a tub of fat-free Greek yogurt can create a high-protein, low-Syn dessert. You can even mix in some sweetener for extra sweetness.

The Verdict: How to Enjoy Custard on Slimming World

Custard does not have to be off the menu when following Slimming World. The key is to be mindful of your choices. Homemade recipes using skimmed milk from your Healthy Extra allowance and sweetener offer the lowest Syn options. If you're opting for convenience, always check the Syn value of ready-made pots, as values vary significantly. Smart alternatives, such as warmed Alpro vanilla custard, provide a satisfying treat with minimal Syn impact. By making informed decisions, you can continue to enjoy custard with your favourite desserts while still successfully following your weight loss plan. To explore more Slimming World-friendly dessert ideas, you can visit the official Slimming World website.

Note: Always check the most up-to-date Syn values on the official Slimming World app or website, as figures can change.

Frequently Asked Questions

No, custard is not a 'Free Food' on the Slimming World plan. All forms of custard have a Syn value, which varies based on the ingredients used (e.g., milk, sugar) and whether it's a homemade or ready-made product.

To make a low-Syn homemade custard, use your milk from your Healthy Extra 'A' allowance (or Syn it), substitute sugar with sweetener, and use a thickening agent like a small amount of cornflour. The official Slimming World blog has recipes for low-Syn versions.

The Syn value depends on the brand and size. For example, a 125g pot of Alpro vanilla custard is often cited as 1 Syn, while a 120g pot of Ambrosia Light is reported to be 4.5 Syns. Always check the specific product.

Yes, you can use your Healthy Extra 'A' milk allowance when making homemade custard to reduce the overall Syn value. Any milk used beyond this allowance must be Synned.

A great low-Syn alternative is warmed, fat-free vanilla yogurt. Brands like Alpro also offer low-Syn vanilla dessert pots that taste like custard. Another option is to add custard flavour drops to fat-free Greek yogurt.

To calculate the Syns for custard powder, you must account for the Syns of both the powder and the milk or sugar used to make it. Always refer to the official Slimming World Syns calculator for the specific brand you are using.

Many people find that low-Syn alternatives, particularly those made with sweetener and flavourings, are very satisfying and a good replacement for traditional, higher-Syn custard. The Alpro vanilla custard, for instance, is highly rated by many users.