The coffee diet is a relatively new diet plan that’s rapidly gaining popularity.
It involves drinking several cups of coffee per day while restricting your calorie intake.
Some people have reported short-term weight loss success with the diet. However, it has some significant downsides.
This article reviews the coffee diet, including its potential benefits, downsides, and whether it’s healthy.
RATING SCORE BREAKDOWN
- Overall score: 3.25
- Fast weight loss: 3
- Long-term weight loss: 2
- Easy to follow: 4
- Nutrition quality: 4
BOTTOM LINE: The coffee diet emphasizes coffee alongside whole foods while restricting processed foods and calories. Though it may aid weight loss, you’ll have a high risk of weight regain. Plus, its high amounts of caffeine may have side effects.
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 per day 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 elderly people.
He believes their health and longevity is a result of their high intake of antioxidant-rich coffee.
How it works
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 would 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 you replace one meal per day 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, which is 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.
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 per day, replace one meal with a green smoothie, and focus on low-fat, high-fiber meals and snacks.
Coffee is rich in caffeine and antioxidants called polyphenols, which have several health benefits, including decreased inflammation and free radical damage (1).
When it comes to boosting weight loss, coffee appears to have two potential benefits — decreasing appetite and increasing metabolism.
May decrease appetite
Dr. Arnot asserts that coffee can suppress your appetite, thereby 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 (3).
However, consuming coffee 3–4.5 hours before eating appears to have no effect on how much you eat at the next meal (3).
A study in 33 people who were either overweight or normal weight found that drinking coffee lowered calorie intake in those who were overweight (5).
Over 3 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 those who were overweight drank 6 ounces (200 ml) of coffee, they consumed significantly fewer calories afterward, compared with when they drank water or coffee with half the caffeine (5).
Conversely, one study in 12 people found there were no differences in calorie intake or appetite between those who drank caffeinated coffee, decaffeinated coffee, or a placebo beverage prior to a meal (6).
Caffeinated coffee may help decrease calorie intake for some people, but more research is needed before definitive claims can be made.
May increase metabolism
Caffeinated coffee, in particular, may increase the number of calories and amount of fat you burn, making it easier to lose weight (7).
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% (7).
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 (8).
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 (4).
However, much of the research on coffee and metabolism was done in the 1980s and ‘90s. More recent research would help strengthen these findings. Furthermore, there is little recent evidence to support some of Dr. Arnot’s stronger claims (9, 10, 11).
Summary Research indicates coffee may aid weight loss by decreasing your appetite and calorie intake, all while increasing the number of calories you burn. However, more research is needed to fully understand how coffee affects weight control.
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.
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.
One observational study looked at 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 (12).
Furthermore, many important electrolytes can be lost with fluid, including potassium. Losing too much potassium can lead to a condition called hypokalemia, which can affect your muscle control and heart health. However, coffee-induced hypokalemia is rare (13).
Although drinking excessive amounts of caffeinated coffee can be harmful, caffeine intake of up to 400 mg per day — or about 4 cups (960 ml) of coffee — is generally considered safe (17).
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 a number of changes that your body goes through when you restrict calories (18).
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 (18).
Leptin is a hormone that promotes feelings of fullness and sends signals to 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 (20, 21, 22).
For these reasons, it’s very difficult to lose weight on diets that require you to significantly reduce your calorie intake, such as the coffee diet. The end 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 5 years of ending their diet (23, 24).
Not safe long-term
According to testimonials, people typically follow the coffee diet for two to seven weeks.
In fact, it may be unsafe over the long term for several reasons.
The coffee diet is also a low-calorie diet, which can make it hard to lose weight and successfully keep it off (18).
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 comes with significant downsides. It 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.
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 the weight you lost (18).
Successful weight loss diets often involve only a small calorie restriction, which results in slower, more sustainable weight loss and lessens the negative metabolic changes associated with calorie restriction (25, 26).
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.
The coffee diet encourages you to drink at least 3 cups (720 ml) of coffee per day while restricting calorie intake.
Though it may result in short-term weight loss, it’s not a healthy diet in the long run.
It can lead to weight regain and adverse effects from excessive caffeine intake.
You may still enjoy the health benefits of coffee, but stick to the safe limit of 4 cups (960 ml) per day or less.
For safe and healthy weight loss, you should avoid restrictive programs, such as the coffee diet, in favor of more sustainable plans.