Losing belly fat is a goal for many people. Excess abdominal fat, also called visceral fat, has been linked to an increased risk of heart disease, type 2 diabetes, and other chronic conditions (1, 2). For this reason, finding ways to reduce belly fat has become a popular weight loss strategy.
Some claim that grapefruit juice is one such belly fat-burning food. Proponents say it contains compounds that boost metabolism and reduce appetite.
This article reviews the evidence on grapefruit juice and weight loss. It also provides tips on incorporating it into your diet without side effects.
What is grapefruit juice?
Grapefruit is a citrus fruit with a taste that can range from bittersweet to sour. Grapefruit juice is made by squeezing the fruit and consuming its pulp and liquid contents.
Like other citrus juices, grapefruit juice is rich in antioxidants like vitamin C, which may help protect against cell damage caused by free radicals (3).
It’s also high in beneficial plant compounds called flavonoids, which have been associated with improved insulin sensitivity, decreased inflammation, and a lower risk of heart disease (4).
However, what sets grapefruit juice apart is its unique chemical makeup, which is thought to affect how the body metabolizes certain medications. This has earned it a reputation as a potential “fat burner.”
Does it burn fat?
The notion that grapefruit juice has special fat-burning properties can be traced back to a 2006 study.
In the study, 91 obese participants consumed either fresh grapefruit or grapefruit juice before meals for 12 weeks. The grapefruit groups also followed calorie-restricted diets.
At the end of the study, those consuming either fresh grapefruit or grapefruit juice had lost significantly more weight than the control group. Additionally, grapefruit consumption was associated with improved insulin resistance (5).
Since then, several other studies have found that eating fresh grapefruit or drinking its juice before meals may promote feelings of fullness, calorie burning, and weight loss (6, 7, 8).
However, most studies lasted under 12 weeks and included very few participants. More robust research is needed before firmer conclusions can be made.
How it may promote weight loss
Though more research is needed, several theories may explain grapefruit juice’s potential weight loss effects.
May boost metabolism
Eating grapefruit or drinking grapefruit juice may temporarily speed up your metabolism. This is thought to be due to a class of antioxidants in grapefruit called naringin and naringenin.
Animal and test-tube studies suggest these antioxidants may increase levels of adiponectin, a hormone involved in blood sugar regulation and fat breakdown (9).
Additionally, they appear to protect cells from metabolic damage caused by free radicals. This leads to improved insulin sensitivity, which allows cells to metabolize sugar more effectively — a necessity for weight loss (10).
While promising, more human research is needed.
May reduce appetite
Grapefruit juice contains soluble fiber, which forms a gel when mixed with water. This gel slows digestion and reduces appetite, which may automatically lead to eating fewer calories (11, 12).
One study had 41 participants drink grapefruit juice before a meal, while the control group drank water. Those who drank the grapefruit juice consumed 20–29% fewer calories during the meal (12).
Additionally, grapefruit juice’s water and fiber content make it very filling. Drinking it before meals may reduce your appetite and total calorie intake (13).
May impact insulin resistance
Insulin resistance occurs when your body cannot use insulin properly, causing high blood sugar and often weight gain or difficulty losing weight.
Eating grapefruit or drinking its juice can improve insulin resistance by lowering blood sugar after meals and increasing insulin sensitivity (5).
These effects may lead to reduced calorie intake and weight loss — especially around the belly area (14, 15).
That said, some studies found no difference in weight loss between those consuming grapefruit juice and placebos. More studies with larger sample sizes are needed (16, 17).
Effect on belly fat specifically
No studies have directly linked consuming grapefruit juice to decreased belly fat. However, research shows it may cause modest weight loss — which often includes losing belly fat.
Additionally, grapefruit juice has been found to improve insulin resistance. Chronically high insulin levels can cause your body to accumulate visceral fat around your midsection (18).
Therefore, grapefruit juice’s potential to improve insulin sensitivity may indirectly help you lose belly fat. Still, keep in mind that weight loss results are modest and more research is needed.
Other potential benefits
Drinking grapefruit juice may provide several additional health benefits:
- May improve heart health. Studies show grapefruit juice reduces LDL (bad) cholesterol, blood pressure, and risk of ischemic stroke (19, 20).
- May reduce kidney stone risk. Citric acid in grapefruit juice increases urine volume, which can help flush out kidney stones (21).
- May protect against cancer. Grapefruit contains antioxidants that may safeguard cells from damage that can lead to cancer (22).
- May promote skin health. The vitamin C and antioxidants in grapefruit juice can support collagen production and protect your skin from sun damage (23, 24).
Keep in mind that many of these studies observed the effects of consuming all grapefruit products — not just grapefruit juice.
Most studies examining grapefruit juice’s weight loss effects used around 8 fluid ounces (237 ml) before meals.
The timing also appears important. Research shows drinking grapefruit juice 30 minutes to 1 hour before meals is associated with decreased calorie intake during meals.
To boost weight loss, drink 8 ounces (237 ml) upon waking, before each meal, and before bed. Be consistent and drink it daily to maximize potential effects.
Drinking small amounts of grapefruit juice is likely safe for most people. However, consuming large amounts or grapefruit products may cause side effects in some, including:
Compounds in grapefruit can inhibit enzymes involved in metabolizing certain medications. They allow more medication to enter your bloodstream, potentially increasing side effects (25).
There are several classes of medications that interact with grapefruit. If you regularly consume grapefruit products, speak with your healthcare provider to ensure it’s safe for you.
Tooth enamel erosion
Like other acidic drinks, grapefruit juice can slowly damage tooth enamel with regular exposure. Drinking it through a straw may help prevent contact with teeth (26).
Blood sugar spikes
The natural sugars in juice can rapidly raise blood sugar levels. If you have diabetes, monitor your levels closely to avoid extremes in response to drinking grapefruit juice (27).
Reduce intake if losing too much weight
Grapefruit juice may aid weight loss; however, some may find they lose weight too quickly. If this occurs, decrease your grapefruit juice intake.
Vs. grapefruit segments
Eating fresh grapefruit segments and drinking grapefruit juice both appear beneficial for weight loss.
One study compared the effects of consuming half a fresh grapefruit, grapefruit juice, or water before meals 3 times per day for 12 weeks. Both fresh grapefruit and grapefruit juice groups lost significantly more weight than the water group (5).
Therefore, while whole grapefruit and its juice should be equally beneficial, there are some differences:
|Fresh grapefruit segments
|May be easier to consume
|More filling with fiber content
|Lacks beneficial insoluble fiber
|Provides all beneficial fiber
|Higher glycemic index (GI) of 48
|Lower GI of 25
The glycemic index (GI) measures how quickly foods raise blood sugar. A lower GI is associated with fuller hunger and better blood sugar control (28).
Given the difference in GI, consuming fresh grapefruit may result in better appetite and blood sugar control. However, grapefruit juice can be a suitable alternative when fresh grapefruit is inconvenient or unavailable.
Grapefruit juice can be enjoyed on its own, but it also mixes nicely into recipes like smoothies, spritzers, and marinades.
Try these tasty, nutritionist-approved recipes:
Blend grapefruit juice, banana, Greek yogurt, chia seeds, almond milk, and a sprinkle of cinnamon for a filling breakfast or snack.
Sparkling grapefruit spritzer
Mix equal parts grapefruit juice and seltzer water over ice and top with a squeeze of lime for a refreshing cocktail.
Broil halved grapefruit topped with cinnamon for a warm breakfast treat.
Citrus shrimp stir fry
Marinate shrimp in grapefruit juice, sesame oil, garlic, and ginger, then stir fry with veggies.
The bottom line
Animal and human research suggests grapefruit juice before meals may promote feelings of fullness, increase metabolism, and reduce calorie intake. This may lead to modest weight loss.
However, research has not directly linked drinking grapefruit juice to belly fat loss in particular. Nor have the weight loss effects been confirmed in larger, longer-term studies.
While grapefruit juice shows promise as a weight loss aid, keep in mind that any resulting weight loss is likely to be modest. For best results, consume it alongside a healthy diet and active lifestyle.