A Two-Week Fruit Diet

Ready to start a fruit diet? Think twice before taking this step. While it's true that fruits are chock-full of nutrition, they lack certain vitamins, minerals and macronutrients needed for optimal health. Consider adding veggies to the mix to keep your diet varied and prevent nutrient deficiencies.

Fruit diets are promoted as a way to lose weight, cure diseases and flush out toxins. Unfortunately, most claims lack scientific proof.

For example, a 30-year study conducted on 182,145 women and published in the International Journal of Cancer indicates that higher intakes of fruits and vegetables may protect against breast cancer. Women who consumed more than five and a half servings of fruits and veggies daily had a lower risk of breast cancer than those eating fewer than two and a half servings per day.

A January 2016 meta-analysis featured in the Annals of Oncology states that dietary carotenoids and other phytonutrients in vegetables and fruits may lower the risk of lung cancer in smokers. Another study, which appeared in the European Journal of Cancer Prevention in May 2016, has linked these foods to lower rates of pancreatic cancer.

However, no studies indicate that a fruit-only diet can prevent or treat cancer and other ailments. Fruits may protect against diseases when consumed as part of a balanced diet. Furthermore, a two-week fruit diet is unlikely to have major benefits on your health because of its short duration. The key to better health is to eat fruits and vegetables on a regular basis.

Additionally, a two-week, fruit-only diet isn't the best choice for weight loss. Fruits are low in protein, the building block of your cells and tissues; this nutrient supports muscle growth and helps preserve lean mass during periods of energy deficit, aka dieting, keeping your metabolism up. Muscle is more metabolically active than fat, meaning that it requires more energy to sustain itself. The more lean mass you have, the more calories you'll burn throughout the day.

Read more: 7 Unexpected Reasons Why You're Not Losing Weight

Did you know that there are people who eat mainly fruits? This eating pattern is known as the fruitarian diet, and it's more restrictive than vegan and vegetarian diets. As the Cleveland Clinic points out, a fruitarian diet can lead to nutrient deficiencies, tooth decay, metabolic slowdown and even weight gain.

Most fruits are high in natural sugars, such as fructose, and may cause you to eat too much and pack on pounds. The sugar and acids in fruits can damage your teeth and cause decay in the long run.

Fruit sugars also increase your blood glucose levels, which may put you at risk for diabetes, metabolic syndrome and insulin resistance. A two-week, fruit-only diet is unlikely to cause these issues, though.

Several studies conducted over the years suggest that fruits may have anti-obesity effects. According to a review published in the journal Nutrients in October 2016, fruits aid in weight management and make weight loss easier while protecting against heart disease, diabetes and other obesity-related disorders. As the researchers point out, these findings are surprising, considering the high amounts of simple sugars in most fruits.

These foods can help you lose weight in several ways. First of all, they're lower in calories than processed snacks, cookies, ready-made meals and so on. Swapping processed foods for fresh fruits will automatically reduce your calorie intake.

Fruits also contain fiber, leading to increased satiety and improved appetite control. Dietary fiber delays gastric emptying and suppresses appetite, which in turn, may help reduce your daily food intake.

Read more: 19 High-Fiber Foods — Some May Surprise You!

The Nutrients review suggests that certain micronutrients in fruits, such as iron, zinc, vitamin A and vitamin C, may protect against obesity and weight gain. For example, resveratrol — a potent antioxidant in grapes — has been shown to increase fat breakdown, prevent the formation of new fat cells and induce fat cell death. Catechins, caffeic acid, naringenin and other phytochemicals in fruits may exhibit anti-obesity effects, too.

The review also points out that fruits may also cause positive changes in the gut flora due to their high content of fiber and polyphenols. These nutrients may increase the number of good bacteria in the gut and reduce the number of harmful bacteria that promote weight gain. However, more studies are needed to confirm the relationship between fruit consumption and gut health.

A meta-analysis published in BMJ Open in April 2018 suggests that eating more fruits and vegetables may decrease fat mass, body mass index, fat mass index and waist circumference. Higher fruit intakes have been linked to a lower risk of abdominal obesity.

These studies, though, say nothing about fruit-only diets, juicing or the popular 7-day fruit cleanse. Instead, they emphasize fruit consumption as part of a healthy diet. Eating only fruits for two weeks or more will likely increase your vitamin and antioxidant levels, but any weight you lose will find its way back as soon as you return to normal eating.

The daily recommended intake of fruits is at least one and a half to two cups per day. Consume two or three cups of vegetables daily as well. As the Centers for Disease Control and Prevention notes, meeting these guidelines may help lower your risk of diabetes, obesity, cardiovascular problems and cancer.

No single fruit or vegetable leads to weight loss. However, some fruits are better than others when it comes to managing your weight. Lemons, limes, berries, kiwi, rhubarb and watermelon have fewer than 100 calories per serving. Dried fruits, on the other hand, are the highest in sugar and calories.

Read more: 5 Tricky Fruits and How to Eat Them

If you're trying to slim down, fill up on low-carb, low-calorie fruits. Here are some examples:

• Watermelon: 84 calories, 21.1 grams of carbs, 1.1 grams of fiber, 1.7 grams of protein and 0.4 grams of fat per serving
• Blueberries: 39 calories, .8 grams of carbs, 1.6 grams of fiber, 0.5 grams of protein and 0.2 grams of fat per serving
• Strawberries: 47 calories, 11.2 grams of carbs, 2.9 grams of fiber, 0.9 grams of protein and 0.4 grams of fat per serving
• Lemon: 17 calories, 5.4 grams of carbs, 1.6 grams of fiber, 0.6 grams of protein and 0.1 grams of fat per serving
• Grapefruit: 65 calories, 16.4 grams of carbs. 2.5 grams of fiber, 1.1 grams of protein and 0.2 grams of fat per serving
• Rhubarb: 26 calories, 5.5 grams of carbs, 2.2 grams of fiber, 1.1 grams of protein and 0.2 grams of fat per serving (one cup)
• Kiwi: 90 calories, 21.9 grams of carbs, 4 grams of fiber, 2 grams of protein and 1 gram of fat per serving
• Avocado: 80 calories, 4.2 grams of carbs, 3.4 grams of fiber, 1 gram of protein and 7.3 grams of fat per serving

Pay attention to portion sizes. One serving of avocado, for example, is only 1.7 ounces and has 80 calories. A whole avocado, by contrast, is around 7 ounces and boasts approximately 322 calories. If you eat more than you need, the pounds will add up.

Limit fruit juices and dried fruits. Fruit juices are higher in sugar and contain little or no fiber. One cup of orange juice, for instance, boasts 112 calories, 25 grams of carbs and 0.5 grams of fiber. The whole fruit, on the other hand, has 75 calories, 19.3 grams of carbs and 3.4 grams of fiber per serving. Banana chips (dried bananas) deliver a whopping 218 calories per serving (1.4 ounces), while raw bananas have only 112 calories per serving (4.4 ounces).