The coffee diet: Benefits, weight loss, downsides, and more

The coffee diet is a relatively new diet plan rapidly gaining popularity.

It involves drinking several cups of coffee daily while restricting your calorie intake.

Some people have reported short-term weight loss success with the diet. However, it has some significant downsides.

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This article reviews the coffee diet, including its potential benefits, downsides, and whether it’s healthy.

In this article

What is the coffee diet?

The coffee diet was popularized by the book “The Coffee Lover’s Diet” by Dr. Bob Arnot.

In the book, Dr. Arnot claims that drinking coffee several times daily can boost your metabolism, burn more fat, block calorie absorption, and decrease your appetite.

He was inspired to write the book after studying the people living on the small Greek island of Ikaria, which has a large population of healthy older people.

He believes their health and longevity result from their high intake of antioxidant-rich coffee.

How it works

The coffee diet plan involves drinking a minimum of 3 cups (720 ml) of light-roast coffee per day. Light roasts tend to be richer in polyphenol antioxidants than darker roasts.

Dr. Arnot places particular importance on the type of coffee you choose and how it’s brewed. He recommends a lightly roasted, whole-bean coffee that you grind at home and prepare using filtered water.

On the diet, you can have as much coffee as you want — caffeinated or decaffeinated — as long as you reach your 3-cup (720-ml) minimum. However, you should avoid using sugar or cream.

He also recommends replacing one meal daily with a homemade, high-fiber, green smoothie. Suggested smoothie recipes are featured in the book.

Your other meals and snacks should be low in calories and fat and rich in fiber from whole grains, fruits, and vegetables. The author also encourages readers to avoid highly processed foods, such as frozen meals and refined snack foods, in favor of whole foods.

In the book, Dr. Arnot’s sample meal plans contain about 1,500 calories per day, likely much fewer calories than a typical person consumes.

Appropriate meals for this diet would include tofu and vegetable stir-fry over brown rice or a grilled chicken salad with a vinaigrette dressing.

High protein, low carb diet: A complete guide

Some people have reported weight loss success with this diet, likely due to the calorie restriction involved. In addition, some evidence suggests that coffee may aid weight loss.

Summary: The coffee diet was developed by Dr. Bob Arnot, who claims that coffee can help you lose weight. On this plan, you drink at least 3 cups (720 ml) of coffee daily, replace one meal with a green smoothie, and focus on low-fat, high-fiber meals and snacks.

Potential benefits of the coffee diet

Coffee is rich in caffeine and antioxidants called polyphenols, which have several health benefits, including decreased inflammation and free radical damage.

Coffee has two potential benefits for boosting weight loss: decreasing appetite and increasing metabolism.

Decreased appetite

Dr. Arnot asserts that coffee can suppress your appetite, helping you decrease your daily calorie intake.

Some research indicates that this is true to an extent. Drinking coffee shortly before a meal may decrease how much you eat at that meal.

However, consuming coffee 3–4.5 hours before eating does not affect how much you eat at the next meal.

A study on 33 people who were either overweight or normal weight found that drinking coffee lowered calorie intake in those who were overweight.

Over three sessions in the study, each person received breakfast and either water, regular coffee, or coffee with half the caffeine. The regular coffee contained 2.7 mg of caffeine per pound (6 mg/kg) of body weight.

When overweight people drank 6 ounces (200 ml) of coffee, they consumed significantly fewer calories afterward than when they drank water or coffee with half the caffeine.

Conversely, one study in 12 people found no differences in calorie intake or appetite between those who drank caffeinated coffee, decaffeinated coffee, or a placebo beverage before a meal.

Caffeinated coffee may help decrease calorie intake for some people, but more research is needed before definitive claims can be made.

Increased metabolism

Caffeinated coffee, in particular, may increase the calories and fat you burn, making it easier to lose weight.

In one review that included more than 600 people, researchers found that greater caffeine intake was associated with decreased weight, body mass index (BMI), and fat mass.

When participants’ caffeine intake doubled, their weight, BMI, and fat mass decreased by 17–28%.

In another study, 12 adults took a supplement that contained caffeine and polyphenols — two major active components of coffee — or a placebo. The supplement caused participants to burn significantly more fat and calories than the placebo did.

Coffee may also boost the amount of fat you burn from working out.

One study looked at the effects of coffee in 7 healthy men who worked out for 30 minutes, then consumed about 1 cup (250 ml) of either water or caffeinated coffee. Those who drank the coffee burned more fat than those who consumed water.

However, much of the research on coffee and metabolism was done in the 1980s and ‘90s, and more recent research would help strengthen these findings. Furthermore, little recent evidence supports some of Dr. Arnot’s more substantial claims.

Summary: Research indicates coffee may aid weight loss by decreasing your appetite and calorie intake, increasing the number of calories you burn. However, more research is needed to understand how coffee affects weight control entirely.

Downsides of the coffee diet

Coffee contains healthy antioxidants and may help you lose weight by suppressing your appetite and increasing your metabolism. However, the coffee diet has several downsides.

Excessive caffeine

Although decaffeinated coffee is an option on the coffee diet, most people prefer caffeinated coffee. Plus, many of the metabolic benefits of coffee are attributed to caffeine.

However, excessive caffeine intake can result in several health problems, such as high blood pressure.

One observational study examined the association between coffee and blood pressure in more than 1,100 people with high blood pressure.

Those who consumed three or more cups of coffee per day had higher blood pressure readings than those who did not drink coffee.

Caffeine is also a diuretic, which causes you to excrete more fluid through urine. If you drink a lot of coffee, you may need to use the restroom more frequently.

Furthermore, many essential electrolytes can be lost with fluid, including potassium. Losing too much potassium can lead to hypokalemia, affecting muscle control and heart health. However, coffee-induced hypokalemia is rare.

Lastly, excessive caffeine intake has been linked to heart attacks, headaches, insomnia, and increased risks of bone fractures, osteoporosis, and even depression.

Although excessive amounts of caffeinated coffee can be harmful, caffeine intake of up to 400 mg daily — or about 4 cups (960 ml) of coffee — is generally considered safe.

Weight regain is likely

Diet plans that involve a drastic reduction in calorie intake — such as the recommended 1,500 calories per day on the coffee diet — often result in weight regain due to several changes that your body goes through when you restrict calories.

Your body adapts to the number of calories you habitually consume. Thus, when you decrease your calorie intake significantly, your body adapts by slowing your metabolism, reducing the number of calories you burn.

In addition, hormonal changes that occur as a result of calorie restriction may increase your appetite.

Leptin is a hormone that promotes feelings of fullness and signals your brain to stop eating. However, leptin levels in your body can decrease significantly on low-calorie diets, potentially leading to greater hunger and food cravings.

For these reasons, it isn’t easy to lose weight on diets that require you to significantly reduce your calorie intake, such as the coffee diet. The result is often weight regain.

According to some research, about 80% of people who lose weight on a low-calorie diet regain some weight in their first month off the diet. Nearly 100% of people regain all of their lost weight within five years of ending their diet.

Long-term risks

According to testimonials, people typically follow the coffee diet for two to seven weeks.

It may be unsafe over the long term for several reasons.

Drinking large amounts of caffeinated coffee could lead to excessive caffeine intake, which may cause several problems, including insomnia and depression.

The coffee diet is also low-calorie, making it hard to lose weight and successfully keep it off.

Unfortunately, no long-term studies have assessed the safety or effectiveness of the coffee diet.

For these reasons, you should not follow the coffee diet over the long term.

Summary: The coffee diet has significant downsides and could lead to excessive caffeine intake. Furthermore, weight regain is likely on restrictive diets like this one. Currently, no research exists on the diet’s long-term safety or effectiveness.

Is the coffee diet healthy?

Unfortunately, the coffee diet is not an ideal weight loss plan.

Its unlimited coffee intake may lead to excessive caffeine consumption. Moreover, its calorie restriction may cause you to regain your lost weight.

Successful weight loss diets often involve only a tiny calorie restriction, which results in slower, more sustainable weight loss and lessens the negative metabolic changes associated with calorie restriction.

Increasing your protein and fiber intake, decreasing the number of refined sugars you consume, and exercising regularly may help you lose weight and keep it off.

For most people, the most successful weight loss diet is one they can stick to.

Summary: The coffee diet is not the best choice for healthy weight loss. Diet plans that are sustainable are more likely to result in success over the long term.