What does caffeine do to your body?
Caffeine is a central nervous system stimulant that reduces fatigue and drowsiness. It can improve reaction times, concentration, wakefulness, and delay sleep.
Furthermore, caffeine has unique health benefits for the body. For instance, recent studies have shown that caffeine is good for the skin!
Caffeine also can improve performance. Athletes use it just before a race or an intense workout.
Can caffeine help you lose weight?
Caffeine is good for weight loss. It might help you lose weight, decrease Bode Mass Index and body fat percentage (3).
In a 2006 study, published in the American Journal of Clinical Nutrition, scientists suggested that increased caffeine intake may lead to a reduction in long-term weight gain (5).
In a 2015 study, published in the European Journal of Clinical Nutrition scientists found that consumption of caffeinated beverages might support weight loss maintenance (6).
Caffeine can promote weight loss and support weight maintenance partly through thermogenesis and fat oxidation (4).
Caffeine in coffee and tea can stimulate prolonged thermogenesis by the interaction between polyphenols and caffeine (1). That’s a powerful mechanism for managing obesity.
Prefer to consume caffeine from coffee or tea. Avoid energy drinks or soda soft drinks. They tend to be high in calories and sugar, leading to weight gain!
Health benefits of caffeine
Caffeine has anti-inflammatory effects (8). Also, caffeine has long been used to treat pain. Its pain-reduction effects have been studied and found that it can relieve pain up to 40 (8).
Many studies have been conducted on the health benefits of coffee. Coffee is much more than caffeine, though. It is rich in polyphenols and along with tea are the main sources of polyphenols.
How much caffeine do we consume?
Coffee consumption varies worldwide. North European countries, Finland and Norway are the countries that consume the most coffee. People in these countries consume on average 9.6 and 7.2 kg of coffee respectively per year.
Contrary, U.S. citizens consume only 3.1 kg of coffee per year.
What about caffeine?
A study showed that adults in the U.K. consume about 130 mg of caffeine daily (8).
Another study from Japan reported an average daily caffeine consumption of about 260 mg per day in adults (8).
So, it is estimated that we consume between 100-300 mg of caffeine per day.
Coffee, tea, energy drinks, and other soft drinks contribute to the daily caffeine intake.
What’s the caffeine content of green tea?
Tea leaves contain about 2–5% caffeine. The amount of caffeine in tea is determined by the leaf size, the brewing time and the temperature (1).
If you leave the tea leaves longer in the hot water, you’ll get more caffeine.
1 cup of tea contains about 30 mg of caffeine.
Caffeine content of Green tea vs Black tea
Green and black tea both contain caffeine.
If you want to minimize caffeine intake prefer green tea, as it contains less caffeine than black tea:
- 12 mg of caffeine, per 100g for the green tea,
- 20 mg of caffeine, per 100g for black tea.
A cup (240g) of green tea contains about 30 mg of caffeine. On the contrary, a cup of black tea contains about 48 mg of caffeine.
What’s the caffeine content of coffee?
Coffee contains more caffeine than tea. It contains about 40 mg of caffeine per 100g (10). It’s about 100 mg of caffeine per cup.
Decaffeinated coffee has almost no caffeine. 100g of coffee has only 1 mg of caffeine. Even low doses of caffeine may be enough for health benefits, such as glowing skin.
Which coffee variety has the most caffeine?
Robusta variety is the richest in caffeine. It contains between 140–200 mg caffeine per 6-ounce cup.
Arabica variety has less caffeine. It contains only 75–130 mg per 6-ounce cup.
What’s the caffeine content of chocolate?
The amount of caffeine in chocolate varies by the percentage of cocoa:
- 100% cocoa chocolate contains around 240 mg caffeine per 100g. We don’t eat this type of chocolate though, as it has no sugar, and it’s extremely bitter. It’s for baking purposes only.
- 55% cocoa chocolate contains 124 mg caffeine per 100g, and
- 33% cocoa chocolate contains 45 mg caffeine per 100 g (8).
How much caffeine is considered safe?
Healthy adults should consume up to 400 mg of caffeine daily (8). That’s the caffeine content in 4-5 cups of coffee!
Caffeine for pregnant, nursing, or lactating women
For pregnant or nursing mothers the recommended daily intake is lower. The European Commission’s Scientific Committee of Food Safety Authority recommends that pregnant women shouldn’t consume more than 300 mg of caffeine daily (8).
The American College of Obstetricians and Gynecologists limits the recommended daily caffeine intake to 200 mg for pregnant women.
Caffeine for kids and adolescents
The caffeine limit is way less for healthy adolescents. They shouldn’t consume more than 100 mg daily.
Furthermore, kids shouldn’t consume more than 2.5 mg/kg daily.
Side effects of caffeine
Caffeine consumption is relatively safe, for healthy adults. On the other hand, caffeine is present in many products.
Heavy coffee and caffeine intake may potentially be harmful to pregnancy outcomes (7). The caffeine can stay in the body 8 - 16 hours longer during pregnancy than usual (8). This means that the effects of caffeine will be longer-lasting in women and in the fetus.
Moreover, pregnant women should ask their doctor for detailed caffeine instructions, as caffeine may have an effect on the brain development of the fetus.
Also, caffeine can be harmful in cardiac patients (8). Moreover, children, young adults, and people with underlying heart or other health conditions, such as mental illness must take care of the daily caffeine intake (8).
Is caffeine addictive?
If a person experiences caffeine reduction may feel some negative symptoms. People may feel less awake or even have other symptoms, like headaches.
Smokers may encounter more difficulty if they experience caffeine restriction, as they tend to consume more caffeine than non-smokers. That’s because smoking excretes caffeine by increasing liver enzyme activity. So, smokers need a double dose in order, to have the same effect as non-smokers (8).
Can caffeine dehydrate you?
Certainly, caffeine has a diuretic effect. Healthy adults who are consuming between up to 6 mg/kg per body weight of caffeine daily are not likely to be dehydrated (8).
Can caffeine interfere with sleep quality?
Caffeine has a relatively long half-life of 3–7 h in adult (8). So, caffeine stays in our bodies for hours after consumption.
Caffeine can alter sleep, and even worse, it can change the circadian rhythm. Hence, you better avoid caffeine intake at least 5 hours prior to sleeping time.
- NCBI – PMC: Tea polyphenols for health promotion
- Caffeine Intake from Food and Beverage Sources and Trends among Children and Adolescents in the United States: Review of National Quantitative Studies from 1999 to 2011
- The effects of caffeine intake on weight loss: a systematic review and dose-response meta-analysis of randomized controlled trials.
- Bodyweight loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation.
- Changes in caffeine intake and long-term weight change in men and women
- European Journal of Clinical Nutrition: Caffeine intake is related to successful weight loss maintenance
- NCNI-PMC: The Impact of Caffeine and Coffee on Human Health
- The Safety of Ingested Caffeine: A Comprehensive Review
- USDA: Beverages, tea, instant, unsweetened, prepared with water
- USDA: Coffee, brewed