A Complete Guide to the ProLon Fast Diet

The ProLon fast diet, a five-day meal program, might be compelling enough to try if you prefer "fasting with food." The ProLon method is a fasting-mimicking diet: The plan allows you to eat a limited amount of food while shifting your body into fasting mode. 

When you fast, metabolic pathways in your body change to create energy from sources other than food. Your body breaks down glycogen in your liver within the first 24 hours of fasting. It then gets energy from fat and protein.

Fasting can be appealing as a weight-loss strategy, but it also usually means going without food entirely. Read on to learn about the ProLon fast diet, including possible benefits, risks, and considerations.

How the ProLon Fast Diet Works

ProLon is a five-day, fasting-mimicking diet created by Valter Longo, PhD, a professor of gerontology and biological sciences at the USC Leonard Davis School of Gerontology. The plan includes gluten-free and plant-based food that is proprietary and prepackaged.

Longo created an eating plan that activates the body's fasting mode while nourishing your cells after over a decade of studies in animals and humans. ProLon helps support your metabolism, or the processes by which your cells convert food into energy, according to the website.

Fasting diets like ProLon trigger autophagy. Cells break down and get rid of irregular or old proteins and substances in cellular fluid during this process. The cells use the breakdown products as fuel during periods of starvation. Some evidence suggests that autophagy helps increase lifespan.

Guidelines

ProLon is a type of periodic fasting, as opposed to intermittent fasting and time-restricted feeding. Intermittent fasting involves eating a fixed number of calories within a particular period (e.g., 500–600 calories in two nonconsecutive days per week). You narrow your eating window to a specific time, like four to eight hours per day, with time-restricted feeding.

ProLon is a five-day plan providing proprietary, prepackaged food. Each kit provides five boxes, one for each day of the plan. Inside the boxes are the food allowed for that specific day.

The kit includes an instruction sheet outlining how to follow the plan. The plan does not allow you to change the order of the days or swap foods from one day's allotment to another. You can decide how to arrange your daily meals, although ProLon provides a suggested menu card.

ProLon provides foods such as:

• A few supplements, including amino acids, minerals, multivitamins, and omega-3 fatty acids
• Dried soup blends, which require adding hot water
• Proprietary bars made with almonds, macadamia nuts, and pecans
• Pouches of olives and kale flax crackers

The kit also contains herbal teas and a large water bottle used to sip a flavored glycerol-based drink. The plan instructs you to consume the drink on days two through five to maintain fullness.

You can add two lemon wedges to the water, consume all-natural sparkling water with no artificial sweeteners, and drink one cup of black coffee daily. You can also sprinkle one teaspoon of herbs daily into the soup.

Benefits

Calorie-restrictive and fasting diets like ProLon may offer benefits to some people. There's a lack of research on the effects of fasting on human health. Keep in mind that not everyone will benefit in the same ways from this dieting style.

Possible benefits of ProLon include:

• Does not require long-term commitment: You may be ready for ProLon to be over by day five. You might also feel a sense of accomplishment for sticking through it for all five days. The ProLon protocol encourages you to slowly return to solid food on day six.
• Helps improve your mood: Some people may experience a euphoric feeling while completing the plan. Some evidence suggests that fasting has antidepressant-like effects.
• May help you lose weight: Research has found that people who followed ProLon lost belly fat and body weight but maintained lean muscle mass.
• Might support heart health: ProLon may lower blood pressure, LDL ("bad") and total cholesterol, and triglycerides. These are significant risk factors for heart disease, the leading cause of death in the United States. 
• No meal planning: Another benefit of ProLon is that you will be free from making meal decisions for five days since the plan provides all your food.

Is the ProLon Fast Diet Safe?

You may need to practice caution or steer clear of fasting diets, depending on your age and health. ProLon advises not starting the plan if you:

• Are pregnant or breastfeeding
• Are younger than 18 or older than 70
• Have a cough, diarrhea, or fever
• Have a history of an eating disorder
• Show signs of an active infection or are at risk of recurrent infection

Do not start a fasting diet without consulting a healthcare provider if you have health conditions like:

• A history of fainting
• Cancer
• Congestive heart failure
• Diabetes

There are a few safety tips to keep in mind if you start a calorie-restrictive or fasting diet, such as:       

• Avoid activities like being in a hot tub or sauna, driving long distances, and prolonged sun exposure
• Consider scheduling ProLon in the middle of your menstrual cycle if you are a person who menstruates. Fasting may affect your hormones.
• Do not perform strenuous exercise. Instead, opt for light activities like stretching, walking, and yoga.
• Pay close attention to how you feel. Side effects like lightheadedness may occur while fasting.
  

Drawbacks

Some people may see benefits after completing the five-day fast, but ProLon may have some downsides. Possible risks include:

• Limits your options: You may grow weary of eating only packaged foods if you are used to eating a lot of fresh fruits and vegetables.
• May be expensive: One kit costs $190, about $38 per day, which may be pricey.
• Might cause irritability: You may get "hangry" on a calorie-restrictive diet, depending on how many calories you typically need. ProLon provides 1,100 calories on day one and 700–800 calories on days two through five, which can be very extreme. Some evidence suggests that short periods of calorie restriction can lead to irritability and an overall lower positive mood than usual.  

Does Fasting Work Long-Term? 

A risk of intermittent fasting and time-restricted feeding is that people tend to gain back weight after completing the diet. A study published in 2019 found, in contrast, that most people who followed ProLon sustained weight loss results for three months after the study. An essential part of any weight-loss plan is being able to maintain your progress.

ProLon is not a long-term lifestyle. The plan advises that you do not extend the diet past five days or complete more than one cycle per month. ProLon instead encourages repeating the diet "from time to time" after three months.

Experts advise establishing long-term healthy eating habits for weight loss. A balanced diet generally includes fresh fruits and vegetables, lean proteins, low-fat or nonfat dairy, and whole grains.

Try incorporating some of the following tips to help build long-term healthy eating habits:

• Add fiber to your meals: Fiber is an essential nutrient that adds bulk to your meals, helping you feel for a long time. Fiber sources include fruits, nuts, seeds, vegetables, and whole grains.
• Decrease your sodium intake: High-sodium diets may raise your risk of heart attack, high blood pressure, and stroke. Experts advise consuming no more than 2,300 milligrams (mg) of sodium daily. People usually consume most of their sodium intake from salt. Swap out salt for fresh herbs, a squeeze of lemon juice, or spice blends.
• Increase your potassium intake: Potassium is a mineral that supports heart, kidney, muscle, and nerve function. A lack of potassium may decrease calcium in your bones, increase blood pressure, and raise the risk of kidney stones. Try adding potassium to your diet by eating a banana for a snack.
• Limit added sugars: The American Heart Association (AHA) advises that men and women eat no more than 36 and 25 grams (g) of added sugar daily. Too many added sugars may cause heart disease, type 2 diabetes, and weight gain. Natural sugars in fruit and milk give your body energy. Try swapping out sugary drinks with water. Add some sliced cucumbers and fruits for a bit of sweetness.
• Make your meals colorful: Ensure you are eating a balanced meal by diversifying the color of your foods. Colorful fruits and vegetables have various minerals, vitamins, and other nutrients that support health.
• Swap out saturated fats: Replace saturated fats with heart-healthy unsaturated fats, such as low-fat or nonfat dairy options.
• Up your calcium and vitamin D intake: These nutrients help build strong bones. Ensure you get enough vitamin D by drinking dairy beverages fortified with the nutrient.

A Quick Review

ProLon can be an investment in your health. Be sure to examine if it's right for you before you start the plan. Some people may benefit from ProLon. Others may find the calorie restrictions challenging, especially those who need a higher-calorie diet.

Consult a healthcare provider before starting a new diet plan. Following ProLon under the supervision of a registered dietitian nutritionist who can coach you through the five days may provide additional support.