I’m not a regular user of TikTok, but when I heard about the viral coffee and lemon diet, I had to see what it involved.

It wasn’t long into my search before I found dozens of videos of people adding a splash of lemon to coffee in hopes of losing fat.

But there weren’t just videos of people trying the diet, several users shared impressive before and after weight loss photos or claimed that the coffee and lemon diet helped them lose up to five pounds in just one week.

Surely, seeing and reading about the weight loss success of others after doing something as simple as adding lemon to your coffee — especially if you’ve previously struggled losing weight — is enough to evoke anyone to try that same thing.

But before you try the coffee and lemon diet yourself, let’s dive into the research on whether the elixir can actually help you lose fat.

coffee and lemon diet

What is the coffee and lemon diet recipe?

The coffee and lemon diet recipes vary but generally call for:

  • 1–2 tsp of instant coffee
  • 8 ounces (240 mL) of hot water
  • freshly squeezed lemon juice from half a lemon or about 1 tsp of bottled lemon juice

It’s unclear why instant coffee is recommended, but you can likely use any brew method.

No other ingredients such as sugar or creamer are allowed and the coffee cannot be caffeine-free.

The elixir is supposed to be consumed once per day in the morning on an empty stomach for 21 days but some people drink it twice daily, usually again before lunch.

However, some people can’t stomach the drink for the full 21 days since the bitterness of black coffee and the sourness of the lemon aren’t exactly a tasty pairing.

Effect on fat loss

Since there are no studies on the effects of coffee and lemon together on fat loss, here’s a look into the potential fat loss effects of the individual ingredients.

Coffee

Coffee contains several bioactive compounds that have a number of beneficial health effects (1).

Several studies have linked moderate coffee consumption (3–4 cups per day) with a lower risk of diabetes, heart disease, fatty liver, dementia, and certain types of cancer (2, 3).

As a natural source of caffeine, coffee consumption may also promote weight loss.

Caffeine is a nervous system stimulant that temporarily increases metabolism and fat burning (5, 6).

One review of 13 studies with more than 600 people found that an average intake of 360 mg of caffeine — equivalent to about 3.5 cups of coffee — was associated with statistically significant weight loss (7).

But this amount of caffeine consumption only provided an average weight loss of less than one pound (2 kg) after four weeks.

So even if caffeine promoted a meaningful amount of weight loss — which research suggests it doesn’t — you would have to drink at least two to three times more of the coffee than what the diet calls for.

However, the caffeine from coffee has a weak appetite-suppressing effect that may indirectly promote weight loss by decreasing food intake (8, 9).

Lemon

Lemons are rich in vitamin C and various beneficial plant compounds known as polyphenols that have strong anti-inflammatory and antioxidant effects (10).

Lemons are also rich in citric acid, a compound that gives them their tart, sour taste.

The high citric acid content of lemons is also what makes them acidic.

Interestingly, the acidity of lemons has been shown to lower the body’s blood glucose or sugar response to carbohydrates (11).

Beyond these benefits, there is some research to suggest that citrus fruits like lemon or citrus extracts could promote weight loss.

A review of 13 studies found that citrus fruits or citrus fruit extracts significantly reduced body weight and hip and waist circumference when compared with placebo (12).

However, these changes weren’t very impressive and many of the studies also had the participants follow a calorie-restricted diet or exercise.

Most of the studies also used a citrus extract supplement that contains far more polyphenols than what lemon juice alone could provide.

As such, there’s limited evidence to support citrus fruits or citrus fruit extracts — let alone lemon juice — for weight loss.

Should you try it?

There is no evidence to support the coffee and lemon diet for weight loss.

People claiming that the diet helped them lose weight certainly may have lost weight, but it’s not because they added lemon to their coffee.

The only way to lose weight is by consistently eating fewer calories than your body burns.

That said, it’s possible that people who claimed they lost weight did so because they drank the beverage in replace of breakfast or that they ate fewer calories after drinking the beverage before a meal due to its potential appetite-suppressing effect.

Certainly, there is no harm or safety concerns in adding lemon to your coffee, unless you have a condition like GERD or interstitial cystitis where the acidity from the lemon juice could provoke symptoms, but know that doing so won’t directly result in any meaningful weight loss.

The bottom line

Popularized by users on TikTok, the coffee and lemon diet has been promoted as the best-kept secret for fat loss.

Although the caffeine from coffee has been shown to increase metabolism and the polyphenols from citrus fruits like lemon may reduce weight, the overall effects are small and weak.

As such, drinking coffee with a splash of lemon won’t result in any fat loss unless doing so helps you create and maintain a calorie deficit.


Gavin Van De Walle, MS, RD, LN
Gavin Van De Walle, MS, RD, LN

Gavin Van De Walle holds a master's degree in human nutrition and bioenergetics. He is a registered dietitian who aims to arm the public with evidence-based nutrition recommendations so they can make their own educated and informed health decisions.