What makes a bar keto?
A strict ketogenic diet limits net carbohydrates to under 10g per 100g for individual foods. Net carbs are calculated by subtracting fibre from total carbohydrates — this gives a more accurate picture of the carbs that actually impact blood sugar and ketosis.
You can check any product instantly with our keto checker calculator.
Most protein bars market themselves as “low carb” or “high protein” without qualifying for a keto diet. The protein bar category is fundamentally a carbohydrate delivery system with added protein — not a protein product with minimal carbs.
Only 2 qualify
2 out of 70 protein bars qualify as keto-friendly
1. Trek High Protein Choc Caramel
2. Trek High Protein Lotus Biscoff
Both keto-qualifying bars are from Trek and priced identically at £1.85. They achieve low net carbs through high fibre content (28g and 21g respectively) which offsets the total carbohydrate. These are the only two bars at Tesco where net carbs fall below the strict keto threshold.
Carb traps
17 protein bars have 30g+ net carbs despite protein marketing
These bars contain more net carbs per 100g than many chocolate bars:
1. TREK White Choc & Raspberry Flapjacks
2. Myprotein White Chocolate Cookie Bar
3. TREK Salted Caramel Flapjacks
4. Trek Protein Flapjack Cocoa Oat
5. Myprotein Protein Brownie
The worst offenders deliver 2–3x the net carbs of a Grenade bar. TREK flapjacks appear repeatedly because they use oats as a base — high in carbs, high in fibre, but the carbs still dominate.
A TREK flapjack has more net carbs than a Mars bar
TREK White Choc & Raspberry at 45.4g net carbs per 100g exceeds a Mars bar (~40g net carbs). The protein marketing masks the carbohydrate reality.
Best low-carb picks (not strict keto)
If you're targeting low-carb rather than strict keto, here are the top 5 by net carbs:
1. Trek High Protein Choc Caramel
2. Trek High Protein Lotus Biscoff
3. Nature Valley Protein Salted Caramel Nut
4. Nature Valley Protein Peanut & Chocolate
5. Warrior High Protein Bar Caramel Crispy
| Brand | Avg net carbs |
|---|---|
| Nature Valley | 16.1g |
| Warrior | 18.4g |
| Huel | 21.3g |
| Barebells | 21.8g |
Get the full keto protein bar rankings
All 70 bars ranked by net carbs, with macro breakdowns and brand analysis.
What can you do?
If you're following a keto diet, the protein bar aisle at Tesco is almost entirely off-limits. Two Trek bars qualify — everything else needs careful checking.
Use our keto checker calculator to verify any product instantly, or install SpikeSaver to see keto suitability on every product page while you shop on Tesco.com.
Know someone doing keto?