While no beverage will do the work of weight loss for you, adding coffee or green tea to your weight-loss plan may enhance your results somewhat. That said, the key to slimming success is still to reduce calories and engage in regular exercise. Only by consuming fewer calories than you burn for energy will you lose the weight and keep it off.
The Caffeine Factor
Both coffee and green tea contain caffeine, which may increase your metabolism, the speed at which you burn calories, per the Mayo Clinic. It may also temporarily suppress your appetite.
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But while it may help your weight-loss efforts, there's no solid evidence that caffeine alone leads to noticeable weight loss.
Is Caffeine Bad for Weight Loss?
Simply adding caffeine to your diet isn't likely to bring about significant weight loss. You'll still need to eat less and exercise more to lose a substantial amount of weight.
If you're getting caffeine from sugar-sweetened beverages — such as sugary coffee and tea drinks, sweetened iced teas, energy drinks or soda — you're more likely to gain weight, per the Centers for Disease Control and Prevention, especially if you're drinking several of these each day. In fact, limiting your amount of sugar-sweetened beverages can help you maintain a healthy weight.
Switching to diet beverages won't solve this problem, according to a July 2015 study in Journal of the American Geriatrics Society. The researchers found that drinking diet soda was linked to abdominal obesity in older adults — and the more diet soda a person drank, the larger their waist circumference was likely to be.
Keep in mind that caffeine doesn't necessarily agree with everyone, especially when consumed in larger amounts. Some people experience acid reflux when they consume caffeine; it can interfere with some medications and it also may increase blood sugar and cholesterol levels. Other potential side effects include an increased heart rate, trouble sleeping, more frequent urination, depression, anxiety and nausea, according to the U.S. National Library of Medicine, especially if you consume more than 400 milligrams per day. (Coffee contains about 100 milligrams per cup, while a cup of tea may have between 14 and 60 milligrams of caffeine.)
Green Tea Boost
Getting your caffeine from green tea may be a good way to slightly increase your weight loss. Antioxidants — called catechins — in green tea may work together with the caffeine in the tea to provide greater weight-loss benefits than either of these ingredients alone.
Indeed, a December 2013 study in the Journal of Research in Medical Sciences found that drinking four cups of green tea per day decreased body weight and waist circumference. The researchers noted that green tea's compounds have been shown to promote fat oxidation and calorie burn.
And an analysis of 26 randomized controlled trials published May 2020 in Phytotherapy Research found that drinking green tea for longer than 12 weeks is linked to lower body weight and body mass index in people with obesity.
Green Coffee Extract
Although more research is needed, some evidence shows that chlorogenic acid from green coffee beans — that is, coffee beans that have not been roasted — may provide some weight-loss benefit.
In a study published in Diabetes, Metabolic Syndrome and Obesity Targets and Therapy in 2012, participants were given either green coffee bean extract or a placebo over multiple treatment periods. Researchers found that subjects lost significant weight and body fat while taking the green coffee, even without any dietary changes.
Succeeding at Weight Loss
While there's nothing wrong with coffee and tea, the best way to ensure a slimmer waistline is to reduce calories and exercise most days of the week.
Choose filling, low-calorie fare such as fruits and vegetables, whole-wheat breads and pasta and oatmeal. Protein-rich foods such as black beans, salmon and low-fat cottage cheese will also keep you satisfied, as will small amounts of fat from nuts, avocados and olive oil.
Rather than dieting, focus on incorporating these choices into your everyday life — this will make it easier to maintain a healthy weight for good.
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- Mayo Clinic: "Does caffeine help with weight loss?"
- U.S. National Library of Medicine: "Caffeine"
- Centers for Disease Control and Prevention: "Get the Facts: Sugar-Sweetened Beverages and Consumption"
- Journal of the American Geriatrics Society: "Diet soda intake is associated with long-term increases in waist circumference in a bi-ethnic cohort of older adults: The San Antonio Longitudinal Study of Aging"
- Journal of Research in Medical Sciences: "The effects of green tea consumption on metabolic and anthropometric indices in patients with Type 2 diabetes"
- Phytotherapy Research: "The effect of green tea supplementation on obesity: A systematic review and dose–response meta‐analysis of randomized controlled trials"
- Diabetes, Metabolic Syndrome and Obesity Targets and Therapy: "Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects"