Do juices cause weight gain?
Juices have become an increasingly popular beverage choice in recent years. Walk into any supermarket or cafe and you’ll likely find a wide selection of fresh, bottled, and even cold-pressed juices. While juices can provide important vitamins and minerals, many people wonder if drinking juice leads to weight gain.
The Basics of Juice
Juice is made by extracting the liquid from fruits and vegetables. This liquid contains most of the vitamins, minerals, and plant chemicals (phytonutrients) found in the fruit but contains little to no fiber. For example, an 8 ounce glass of orange juice may contain the juice of 2-3 oranges but none of the fiber.
There are several broad categories of juice:
- Fruit juices like orange, apple, grape, etc.
- Vegetable juices like tomato, carrot, green juices, etc.
- Juice blends which mix fruit and vegetable juices
- 100% pure juices with no added sugars, sweeteners, or ingredients
- Juice drinks or juice cocktails which contain added sugars, flavors, and other ingredients besides the juice
In this article, we’ll focus on pure fruit and vegetable juices without added sweeteners or ingredients.
Calories and Sugar in Juice
The first thing to understand about juice is its calorie and sugar content. Fruit and vegetable juices can contain a large amount of natural sugars, even with no added sugar. For example:
| Beverage | Serving Size | Calories | Sugar (g) |
|---|---|---|---|
| Orange juice | 1 cup (8 oz) | 112 | 21 |
| Apple juice | 1 cup (8 oz) | 114 | 25 |
| Carrot juice | 1 cup (8 oz) | 94 | 22 |
| Tomato juice | 1 cup (8 oz) | 41 | 10 |
As you can see, an 8 ounce glass of juice can contain over 20 grams of sugar and around 100 calories. Over the course of a day, drinking several glasses of juice can quickly add up in calories and sugar.
Fiber and Fullness
One of the biggest differences between drinking juice versus eating whole fruits and vegetables is the lack of fiber. Fiber is a type of carbohydrate that our bodies cannot digest. It passes through the digestive system intact.
Fiber provides several important functions, including:
- Slows digestion, allowing you to feel full for longer after eating
- Helps regulate blood sugar levels
- Promotes gut health and digestion
- Lowers cholesterol
When you drink juices, you remove nearly all the fiber naturally present in fruits and vegetables. This can lead to a lack of fullness after drinking juice compared to eating the whole produce.
For example, a medium orange contains about 3 grams of fiber compared to 0.5 grams in an 8 ounce glass of orange juice. An apple contains about 4 grams of fiber, but apple juice has virtually no fiber. Without all that filling fiber, it’s not hard to drink 2-3 servings of juice very quickly.
Blood Sugar Spikes
Another consequence of removing fiber from fruit and vegetable juices is the effect on blood sugar. The natural sugars in juice are released very quickly into the bloodstream since there is no fiber to slow absorption. This can lead to rapid spikes in blood sugar after drinking juice.
These surges in blood sugar then cause the pancreas to release large amounts of insulin to lower blood sugars. This rollercoaster effect can leave you feeling shaky, irritable, and hungry again soon after drinking sugary juices. Over time, these blood sugar fluctuations can contribute to insulin resistance.
Compare drinking juice to eating a whole fruit like an apple. The fiber in the apple means it takes much longer to chew and digest. The fibers slow the release of sugar into the bloodstream, preventing major spikes. This helps you maintain steady energy levels and avoid sugar crashes.
Lack of Protein and Fat
Two other nutrients that affect fullness are protein and fat. These nutrients take longer to digest, helping you feel satisfied for a prolonged period after eating. Whole fruits and vegetables contain small amounts of protein and fat.
When you extract the juices, almost all the fat and protein are removed. So juice lacks the protein and fat that would be present if you ate the whole produce. This difference can influence appetite regulation after drinking juice.
High Calorie Intake
Due to the lack of fiber, protein, and fat, it is very easy to consume a lot of extra calories from juices without feeling very full. For example, drinking two large glasses of orange juice per day provides an extra 224 calories. Over a week or month, those extra calories can really add up.
Juices also lack the chewing resistance of whole foods. This makes it easy to consume juices very quickly. You could easily drink a large glass of fruit juice in 5 minutes. But try eating 5 oranges or apples in 5 minutes – it would be nearly impossible.
The faster you consume calories, the less time your body has to register fullness and shut off your appetite. So juices can lead to excess calorie intake simply due to their liquid form.
Poor Satiation
Satiation refers to how well a food satisfies your hunger and curbs your desire to continue eating. Whole fruits and vegetables have a high satiation value due to their water content, fiber, protein, and fat. Juices lag behind.
One study compared the satiation value of a blended fruit and vegetable juice compared to the whole produce:
| Beverage/Food | Calories | Satiation Index |
|---|---|---|
| Blended juice | 208 | 40 |
| Whole produce | 208 | 100 |
The whole fruits and vegetables were 250% more satiating than the blended juice, even though they contained the same calories. This demonstrates how juices can lack the ability to trigger feelings of fullness and satisfaction compared to eating solid produce.
Higher Calorie Density
Calorie density refers to the number of calories in a given weight of food. Whole fruits and vegetables have a low energy density due to their high water and fiber content. These components add weight and volume without adding calories.
Juices have a higher calorie density because the fiber is removed. You end up with more calories packed into a smaller volume of liquid. Here’s a comparison of the calorie density for some common produce items vs their juices:
| Food | Calories per Gram |
|---|---|
| Orange | 0.5 |
| Orange juice | 0.7 |
| Apple | 0.3 |
| Apple juice | 0.5 |
| Carrots | 0.3 |
| Carrot juice | 0.7 |
You can see how removing the fiber significantly concentrates the calories. With their higher calorie density, it’s easy to drink extra calories from juice while believing you’re only consuming a modest amount.
Lack of Chewing
Chewing your food is connected to appetite regulation. The act of chewing sends signals to your brain about an impending influx of calories. This allows your brain to prepare and release the appropriate digestive hormones.
Since juice requires no chewing, this regulatory process is disrupted. Without the anticipation of calories arriving, your body may not release sufficient hormones like cholecystokinin (CCK) to trigger feelings of fullness.
One study showed that participants who chewed almonds longer before swallowing released more CCK and felt fuller afterward compared to people who chewed less.
With juices, there is zero oral processing time. This means juices may not provide the appetite-reducing benefits generated by chewing solid food.
Rapid Absorption
Another downside to juices is the speed at which the sugars enter your bloodstream after drinking them. The lack of fiber, protein, and fat means juices can be absorbed extremely quickly.
For example, one study tested glycemic responses by having participants ingest a sweet potato in various forms:
| Test Food | Peak Blood Sugar | Time to Peak |
|---|---|---|
| Boiled sweet potato | 83 mg/dL | 49 min |
| Pureed sweet potato | 104 mg/dL | 31 min |
| Sweet potato juice | 142 mg/dL | 15 min |
The juice resulted in much faster and higher blood sugar spikes compared to the boiled or pureed potato. This rapid absorption means juices digest quickly, providing an influx of calories without promoting satiety.
Limited Evidence in Humans
Most of the evidence related to juices and weight gain comes from short term studies examining blood sugar responses and satiety hormones. But few long term randomized controlled trials have been conducted in free-living humans.
Some observational studies have associated 100% fruit juice intake with weight gain, especially in kids. But these types of studies cannot prove cause and effect.
Overall, more research is needed examining how juices affect body weight control when consumed regularly as part of a normal diet.
Potential Benefits for Weight Loss
Despite their potential downsides, there are a few scenarios where juices may benefit weight loss:
- Low calorie juices: Juices made primarily from low sugar vegetables (like kale, cucumber, celery) can provide important nutrients with minimal calories, potentially aiding weight loss.
- Meal replacements: Using fresh juices as a low calorie temporary meal replacement for breakfast or lunch can help reduce overall calorie intake.
- Detox/cleanses: Some people use short term juice fasts or detoxes claim success with temporary weight loss. However, most of this is water weight that is quickly regained.
- Satiety before meals: Some evidence suggests drinking vegetable juice 30 mins before meals can modestly reduce intake at the meal.
However, there are drawbacks to prolonged juice fasts or cleanses. These include potential muscle loss, malnutrition, fatigue, and rebound overeating afterward.
Tips for Drinking Juice Without Weight Gain
Here are some tips to help prevent weight gain when drinking juices:
- Stick to small portions like 4-8 ounces.
- Avoid drinking juice by itself. Have it alongside food or a meal.
- Mix juices with water or carbonated water to dilute the sugar content.
- Choose low sugar vegetables instead of fruits for juice ingredients.
- Eat fiber and protein at the same meal as drinking juice.
- Avoid juicing fruits with the highest sugar like grapes, mangos, and pomegranates.
- Don’t juice fruits already high in liquid like watermelon and oranges.
- Consider blending whole fruits and veggies instead of just juicing.
- Drink homemade juices right after making them to avoid oxidation of nutrients.
Summary
Juices can play a role in a healthy diet, but should not replace whole fruits and vegetables. Fibers, proteins, fats, and chewing resistance all influence how filling a food is and help regulate appetite.
Juices lack many of these important factors, making them less filling for their calorie amount. For this reason, drinking juices frequently or in large amounts can potentially lead to over-consumption and weight gain over time.
Moderating juice portions, choosing low sugar vegetables, and drinking juices alongside complete meals can help prevent excessive calorie intake from juices.
More long term human studies on fruit and vegetable juices are needed. But based on the current evidence, it seems juices are not an optimal replacement for eating solid plant foods.