Customers describe noticeable benefits during multi-day fasts, including mental clarity and fewer cravings by day four or five. Many praise the taste and the convenience of bars, shakes, and multi-day kits. Several reviews mention recurring billing, unwanted shipments, and late deliveries. Shipping fees and a clunky checkout often make ordering harder.
Examples from available reviews (May 2022 – Mar 2026).
Reviewer experienced mental clarity by days four or five and endorses science.
“Day 4 or 5 the mental clarity is the best part.”
Repeated purchases with easy ordering and perceived metabolic health improvements.
“This is my 12th Fasting Mimicking Diet purchase in 13 months.”
Customer was charged for three kits and cannot get resolution.
“Prolon charged me for 3 kits instead of just the 1 kit I wanted.”
Confusing cart process and discounts; forced into subscription without choice.
“It was unclear how to add the original FMD box to the cart.”
Billing and autoship issues drive most negative feedback. Multiple reviewers report surprise charges, shipments continuing after cancellation, and trouble getting refunds. Other reviews share better experiences, including reps replacing missing items or fixing problems quickly.
Value opinions depend on shipping costs and clear pricing. Some reviewers say shipping fees or unannounced price changes wipe out promo savings. Others say clear discounts and free-shipping deals make the program affordable.
Most usability complaints center on checkout and account steps. Reviewers mention confusing cart behavior, a slow site, and problems using FSA/HSA payments or dealing with split charges. In contrast, several customers describe smooth ordering and an easy-to-use site.
Product quality stands out as a consistent positive theme. Users say the bars, shakes, and kit foods taste good and help them stick with short-term fasts. Repeat buyers also mention steady quality across recurring orders.
Communication trends positive, with specific examples of helpful, informative support. Some reviewers point to an active community and responsive staff. A small number mention promised messages that never came or replies that did not help.
Reviews split between strong product results and weak operations. Many customers highlight physical results and good taste, while others focus on serious billing and shipping problems. That contrast shapes the overall view of the buying experience.
For each review, the core experience based on original source reviews.
Sources: Trustpilot (40) · Collected.reviews (1) · Quotes shortened · As of: March 2026
I recently had the pleasure of trying Fast Bar, and I must say that it exceeded my expectations. As someone who is new to intermittent fasting, I was looking for a product that could provide me with the necessary nutrients without breaking my fast. Fast Bar did just that.
The bar itself has a delicious taste and texture, making it an enjoyable snack to eat during your eating window. One thing that stood out to me is the fact that it uses premium ingredients which are scientifically formulated to support weight management and a healthy lifestyle.
As stated on their website, this bar is more than just for fasting goals - it can also be used as a nutritious snack anytime throughout your day. Whether you need fuel before or after a workout or simply want something healthy to satisfy your hunger, Fast Bar has got you covered.
I appreciate the convenience of having such an easy-to-grab option when life gets busy. It saves time on meal prep and ensures I'm getting high-quality nutrition in between meals.
Overall, I highly recommend giving Fast Bar a try!
This page combines submitted experiences with public reviews from platforms such as Google, Trustpilot, etc. Recurring points are summarized without changing the content of reviews.
Fast Bar makes nutrition bars and related meal products for people doing short-term fasts or using meal replacements. It sells both kits and individual items through an online store. Shoppers can order once or sign up for recurring deliveries on the website. Fast Bar ships bars, shakes, and multi-day kit items to customers and takes online payments.