Skip to Content

When should I drink grapefruit juice to lose weight?


Grapefruit juice has long been touted as a weight loss aid. The claim is that it can help boost metabolism and burn fat. But does science back this up? And when is the best time to drink grapefruit juice for weight loss? Let’s take a closer look.

How Grapefruit Juice May Promote Weight Loss

There are a few ways that grapefruit juice may potentially help with weight loss:

Increasing Metabolism

Some studies have found that grapefruit juice can give your metabolism a boost. This is likely due to a compound in grapefruit called nootkatone. Animal studies show that nootkatone may activate AMPK, an enzyme involved in metabolism and energy production [1].

By increasing metabolism, grapefruit juice may help your body burn slightly more calories throughout the day. However, the effect is likely to be modest.

Reducing Insulin Levels

Grapefruit juice is high in antioxidants like naringin and naringenin. Research shows these antioxidants may help reduce insulin resistance by improving how your cells respond to insulin [2].

Having lower and healthier insulin levels may promote weight loss. That’s because high insulin can increase fat storage and hunger.

Suppressing Appetite

Some compounds in grapefruit may also suppress appetite. For example, drinking grapefruit juice before meals may increase levels of cholecystokinin (CCK), a hormone that promotes feelings of fullness [3].

Additionally, naringin and naringenin have been found to regulate the production of ghrelin, the “hunger hormone” that stimulates appetite [4].

Best Time to Drink Grapefruit Juice for Weight Loss

Keeping those potential mechanisms in mind, here are some tips on when to drink grapefruit juice if you’re trying to lose weight:

1. Before Meals

Drinking grapefruit juice about half an hour before meals may be most effective for appetite suppression. Studies show grapefruit juice can boost levels of satiety hormones like CCK right before eating [3].

Having grapefruit juice as an appetizer may reduce your overall calorie intake at that meal by making you feel fuller sooner.

2. For Breakfast

Drinking grapefruit juice in the morning may give your metabolism an early boost and increase fat burning throughout the day.

One study had participants drink half a grapefruit’s juice before their breakfast. After 12 weeks, they lost an average of 3.6 pounds compared to the placebo group [5].

Starting your day with grapefruit juice may set you up for success portion and calorie-wise.

3. Post-Workout

Some research suggests having grapefruit juice after exercise may help with recovery and muscle building.

In one study, drinking grapefruit juice after weight training helped participants regain strength faster compared to a placebo. This was likely due to its ability to reduce inflammation and oxidative stress [6].

Grapefruit juice may support the immune system after workouts, allowing your muscles to heal and grow.

Best Type of Grapefruit Juice for Weight Loss

Not all grapefruit juice is created equal when it comes to weight loss. Here are some tips on selecting the best kind:

Choose Fresh Squeezed

Freshly squeezed grapefruit juice retains the most nutrients and beneficial plant compounds compared to store-bought juices. Juice made from concentrate can lose antioxidant content in processing.

If you can’t freshly squeeze it yourself, look for 100% grapefruit juice with no added sugars or preservatives.

Opt for Red or Pink Grapefruit

Red and pink varieties of grapefruit tend to be lower in sugar and higher in antioxidants than white grapefruit [7].

In one study, people drinking fresh red grapefruit juice lost more weight than those drinking white grapefruit juice, likely due to differences in antioxidant content [8].

Watch the Calories

While grapefruit juice has benefits for weight loss, it’s still fairly high in natural sugars. A 8 oz glass can contain over 20 grams of sugar [9].

Be mindful of portion sizes and calorie content if weight loss is your goal. Limit intake to about 4-8 oz at a time.

Avoid Added Sugars

Many store-bought grapefruit juices have extra sugars added as sweeteners. Read labels carefully and pick 100% grapefruit juice only.

Added sugars like high fructose corn syrup can sabotage weight loss by leading to overeating and fat storage [10].

How Much Grapefruit Juice Should You Drink Per Day?

There’s no standardized recommendation for how much grapefruit juice to drink daily. However, here are some general guidelines based on research:

– 1 glass (about 8 oz) with breakfast may boost metabolism and fat burning [5]

– 1 glass (about 8 oz) pre-meal may aid appetite control [3]

– 4-8 oz after workouts may support recovery and muscle growth [6]

So around 16-24 ounces (2-3 glasses) per day may be a reasonable amount to potentially see results. Make sure to account for the calories in grapefruit juice when planning your diet.

Grapefruit Juice Diet Plan Example

Here is a sample 1-week grapefruit juice diet plan for weight loss:

Time Drink
7 AM 8 oz fresh grapefruit juice
8 AM Breakfast omelette with veggies
10 AM Snack – Greek yogurt and berries
12 PM 8 oz fresh grapefruit juice
12:30 PM Lunch salad with chicken
3 PM Snack – Hummus and carrots
6 PM 8 oz fresh grapefruit juice
6:30 PM Dinner – Fish and quinoa
8 PM 8 oz fresh grapefruit juice

Drinking a glass of grapefruit juice before meals may help control hunger and calories at those meals. Having some post-workout helps recovery.

Potential Side Effects of Grapefruit Juice

Grapefruit juice is likely safe for most people when consumed in moderation. However, there are some potential side effects to be aware of:

– Medication interactions – Grapefruit can affect how some medications are broken down in your body. Check with your doctor.

– Heartburn – Grapefruit juice is acidic and may irritate reflux.

– Tooth enamel erosion – Grapefruit is acidic and could wear down enamel over time. Use a straw to prevent contact with teeth.

– Blood sugar spikes – Grapefruit has a high glycemic index and could spike blood sugar in some individuals.

– Sun sensitivity – Grapefruit contains compounds that may make skin more sensitive to UV rays.

Should You Try the Grapefruit Diet?

The Grapefruit Diet is a short-term fad diet that involves eating grapefruit with every meal to promote quick weight loss. However, it is an extremely restrictive plan.

Here is an overview of the traditional Grapefruit Diet plan:

Breakfast Half grapefruit + 2 eggs + bacon/meat
Lunch Half grapefruit + meat + salad
Dinner Half grapefruit + meat + veggies
Snacks Grapefruit

While this diet may lead to fast initial weight loss due to calorie restriction, it is not sustainable or healthy long term. It may even slow your metabolism.

A better option is to include grapefruit juice or fruit as part of a balanced, portion-controlled diet with plenty of lean protein, whole grains, fruits and vegetables. This provides sustainable weight loss without deprivation.

The Bottom Line

When trying to lose weight, the best time to drink grapefruit juice is about half an hour before meals. This capitalizes on grapefruit’s appetite and blood sugar controlling abilities. Drinking it for breakfast and after workouts may also be beneficial.

Aim for around 2-3 glasses (16-24 oz) of fresh grapefruit juice daily as part of a reduced calorie diet. But be mindful of medication interactions and potential side effects.

While the classic Grapefruit Diet is too restrictive, having a glass of grapefruit juice 1-2 times per day can be a smart component of a healthy weight loss regimen.