Diet Coke: Calories, Nutrition and Health Benefits

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Diet Coke has 0 calories, 0g sugar, 0g carbs and 40mg sodium in a 12 fl oz can, plus 46mg of caffeine. It is sweetened with aspartame, so it adds no carbohydrate and does not raise blood sugar directly. Regular Coca-Cola has 140 calories and 39g sugar in the same can.

Quick Nutrition Facts

Per 1 can (12 fl oz, 355 mL)

Nutrient	Amount
Calories	0 kcal
Protein	0g
Carbohydrates	0g
Fiber	0g
Sugars	0g
Fat	0g
Sodium	40 mg

Macronutrient Breakdown

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NUTRITIONIST'S INSIGHT

A can of Diet Coke adds nothing to your calorie or carb count, which makes it an easy swap for regular cola when you want to cut added sugar. The tradeoffs are small: 46mg of caffeine (about half a cup of coffee, and more than Coke Zero Sugar), 40mg of sodium, and phosphoric acid, which is hard on tooth enamel if you sip it all day. The WHO's 2023 guideline advises against relying on non-sugar sweeteners for long-term weight control, so use it as a step away from sugary drinks and keep water or sparkling water as most of what you drink.

Myth Busters

MYTH #1: Diet Coke spikes blood sugar like regular Coke

TRUTH: The label shows 0g carbohydrate and 0g sugar per can, so there is nothing to convert into glucose. Regular Coca-Cola has 39g of sugar per 12 fl oz can. Diet Coke: Nutrition Facts, Caffeine and Sizes; Coca-Cola Original: Nutrition Facts & Ingredients

MYTH #2: Aspartame in Diet Coke is proven to cause cancer

TRUTH: In July 2023 IARC classified aspartame as possibly carcinogenic (Group 2B) on limited evidence, while JECFA kept the acceptable daily intake at 40 mg per kg of body weight. A 70 kg adult would need roughly a dozen or more cans a day to reach that limit. Aspartame hazard and risk assessment results released; Aspartame and Other Sweeteners in Food

MYTH #3: Zero-calorie soda guarantees weight loss

TRUTH: The WHO's 2023 guideline found no long-term body-fat benefit from non-sugar sweeteners in adults or children and advises against using them for weight control. Swapping a sugary soda for Diet Coke cuts calories that day, but it carries no weight-loss guarantee. WHO advises not to use non-sugar sweeteners for weight control; WHO guideline on the use of non-sugar sweeteners

MYTH #4: Diet Coke has less caffeine than regular Coke

TRUTH: A 12 fl oz can of Diet Coke has 46mg of caffeine, more than the 34mg in regular Coca-Cola or Coke Zero Sugar. A Caffeine Free version exists with the same zero calories. Diet Coke: Nutrition Facts, Caffeine and Sizes

MYTH #5: Diet Coke and Coke Zero Sugar are the same drink

TRUTH: They are separate formulas. Both are zero-calorie, but Diet Coke has its own lighter flavor and more caffeine, while Coke Zero Sugar was built to taste closer to classic Coca-Cola. Diet Coke: Nutrition Facts, Caffeine and Sizes

NutriScore by Health Goals

Health Goal	NutriScore	Why This Score?
Weight Loss		Zero calories per can makes it a useful replacement for a 140-calorie regular cola. The grade stops at B because the WHO found no long-term weight benefit from sweeteners and it gives no satiety. Diet Coke: Nutrition Facts, Caffeine and Sizes; WHO advises not to use non-sugar sweeteners for weight control
High Protein		0g protein per can. It contributes nothing toward a protein target. Diet Coke: Nutrition Facts, Caffeine and Sizes
Low Carb / Keto		0g carbs and 0g sugar per can, so it fits any carb limit including strict keto. Diet Coke: Nutrition Facts, Caffeine and Sizes
Heart Health		Only 40mg of sodium and no fat, but the WHO guideline notes possible long-term cardiovascular associations with regular sweetener use, based on observational data. Diet Coke: Nutrition Facts, Caffeine and Sizes; WHO advises not to use non-sugar sweeteners for weight control
Diabetes Management		No carbohydrate means no direct glucose load, so it is a better pick than regular cola. The WHO recommendation against sweeteners excludes people with existing diabetes. Diet Coke: Nutrition Facts, Caffeine and Sizes; WHO advises not to use non-sugar sweeteners for weight control
Nutrient Density		No vitamins, fiber, protein or meaningful minerals in a can. Diet Coke: Nutrition Facts, Caffeine and Sizes

PERSONALIZED NUTRITION

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Blood Sugar Response - Diet Coke (1 can / 355 mL)

With 0g carbohydrate and 0g sugar, Diet Coke gives the body no glucose to absorb, so a healthy adult's blood sugar stays near its fasting baseline for the full 2-hour window. Any movement comes from food eaten with it, not from the can. Diet Coke: Nutrition Facts, Caffeine and Sizes; WHO advises not to use non-sugar sweeteners for weight control

Estimated Blood Glucose Response (mg/dL)

Illustrative baseline for a healthy adult drinking one can on its own. Meals eaten with it and individual insulin sensitivity change the real curve.

How to flatten the spike

Log it as 0g carbs, and carb-count the food you drink it with.
Pair it with a meal that has protein and fiber so the meal's carbs rise more slowly.
Use it to replace sugary drinks, not on top of them.
Alternate with water or sparkling water to limit total sweet-taste exposure.

Cultural Significance

Coca-Cola launched Diet Coke in the US in 1982, its first new brand since 1886, and it became the best-selling diet soda in America within a few years. Outside the US it is sold as Coca-Cola Light in many markets, including Spain, Italy and Germany. It is a staple in offices, fast-food orders and cocktail mixers, and a common pick for anyone who wants a cola without sugar.

Compare & Substitute

Diet Coke vs Similar Foods

Nutrient	Coca-Cola Original (12 fl oz)	Coke Zero Sugar (12 fl oz)	Pepsi Zero Sugar (12 fl oz)	Plain sparkling water (12 fl oz)
Calories	140 kcal	0 kcal	0 kcal	0 kcal
Protein	0g	0g	0g	0g
Carbohydrates	39g	0g	0g	0g
Fat	0g	0g	0g	0g

Frequently Asked Questions

How many calories are in Diet Coke?

A 12 fl oz can has 0 calories, 0g sugar and 0g carbohydrate on the US label. Values under 5 calories round to zero, so a can holds about 1 kcal at most.

Does Diet Coke have caffeine?

Yes, 46mg per 12 fl oz can, about half a cup of brewed coffee. Diet Coke Caffeine Free has none.

What sweetener is in Diet Coke?

The US recipe uses aspartame, with caramel color, phosphoric acid, potassium benzoate, natural flavors and citric acid. It carries a phenylketonuria warning.

Can I drink Diet Coke with diabetes?

It contains no carbohydrate, so it does not raise blood glucose directly and counts as 0g in carb-counting plans. The WHO's sweetener guideline does not apply to people with existing diabetes. Ask your care team about daily limits if you drink several a day.

Is aspartame in Diet Coke safe?

JECFA reaffirmed an acceptable daily intake of 40 mg per kg of body weight in 2023, and IARC listed aspartame as possibly carcinogenic (Group 2B) on limited evidence. The FDA says it found no safety concerns at current levels of use.