Update 3/3/20. Phen375 is a weight loss supplement you may have seen advertised on the web. Does it work or is it a scam? Well, it has an ingredient that I have not looked at before and that's what got me interested in it. Why does the supplement contain the letters ‘Phen?” What does that refer to? That's one of the things that I want to address in this review. If you were curious about Phen375 keep reading and be sure to take special note on the section dealing with their money-back guarantee.
Does It Contain Phentermine?
First off we have to deal with the elephant in the room. The “Phen” in the name of the product is an obvious reference to Phentermine, a doctor prescribed, amphetamine-like weight loss medication that was part of the infamous Fen-Phen weight loss drug combination that was removed from the US market in 1997 because it was linked to heart valve problems. Another name for Phentermine is “Adipex-P.”
It appeared that it was the “Fen” part of the drug combination (fenfluramine) rather than “Phen” at the root of the medical issues. Phentermine (Phen) is still prescribed by some doctors.
There is no phentermine in Phen375. The same goes for other weight loss supplements that also bear the phen prefix including:
- PhenTabz (review)
- Phentraburn (review)
That said, one of my rules of thumb is to assume supplements with the prefix “phen” contain stimulants.
The bottom line to all this: phentermine is a prescription drug and drugs are not allowed to be used in dietary supplements in the US.
Phen375 Research
The supplement itself appears to have no published, peer-reviewed clinical evidence that it helps people lose weight. Neither the supplement website nor clinical databases reveal any clinical investigations on the product.
In the absence of research on the product, we have to look at the weight loss research on the ingredients.
Phen375 Ingredients
I called the customer service people who handle Phen375 and was told that each capsule contains 516 mg of a proprietary blend of the following ingredients:
- L-Carnitine
- Caffeine
- Coleus Forskohlii
- Citrus Aurantium
- Cayenne Pepper
- Dendrobium Nobilel Extract
I've listed the ingredients in order as I was told they appear on the Supplement Facts label of the product. Therefore, I assume that ingredients at the top of the list make up most of this 516 mg proprietary blend while those at the bottom are present the least. For example, L carnitine is present first, so it should make up most of the blend.
Looking at the ingredients in the product, it appears Phen375 is supposed help weight loss in 3 different ways:
1. Increase fat burning.
2. Increase transport of fat to where it's burned (the mitochondria).
3. Increase metabolic rate.
I'll address why I think this way in my review of the ingredients below.
I was told that the recommended use is to take 1 capsule per day. Since I could not view an actual label, I can only go by what I was told on dosage.
Since the proprietary blend contains only 516 mg, I'm not sure what the “375” in Phen375 refers to?
L-Carnitine
L-carnitine is a compound that helps us burn fat. It transports fat molecules to the mitochondria so they can be burned for energy. In this way, L-carnitine is basically a taxicab – it transports fat.
The idea behind L carnitine as a weight loss supplement is that by providing more taxicabs, we deliver more fat to where it can be broken down (burned) to make energy.
We make carnitine and its in foods with steak having some of the highest concentration at between 50-160 mg per 4 oz.
Carnitine has been an ingredient in many weight loss supplements over the years. A few of the other supplements reviewed here that also contained this compound include:
See those reviews for additional information.
In this 2011 rat study, 5 grams of L-carnitine (which is more than what's in Phen375) given to rats for 23 days did not help them lose any weight – even though those rats were also fed fewer calories.
So much for rats. What about people?
In 2004 a study was published that involved 36 overweight women. The women were randomly split into two groups: One group received 4 grams (4000 mg) of L-carnitine a day and the other group took a placebo. Both groups walked 30 minutes a day, 4 days a week. At the end of this 8-week study, carnitine did not lead to any more weight loss than those who took the placebo.
Interestingly, these results are just the opposite of this 2003 study of 84 older adults that lasted 30 days. In this study, those who received 4 grams (4000 mg) of L-carnitine a day lost more fat than those who got a placebo (3 pounds vs. 0.5 pounds). Improvements in muscle, cholesterol and triglycerides were also seen.
In another study of 60 overweight women with PCOS, 250 mg of L-carnitine, given for 12 weeks (3 months) was observed to significantly reduce body weight (by about 6 pounds) compared to those getting a placebo.
In a more recent review of 9 previous human studies, the researchers concluded that carnitine supplementation was associated with a 2.9-pound loss in body weight compared to those who did not receive carnitine. That's not much but it is something.
Caffeine
I am not aware of how much caffeine is in Phen375 but since caffeine is the 2nd ingredient in the list, I wonder if it might make up a significant portion of the 516 mg proprietary blend?
Caffeine is a stimulant and might have a mild fat-burning effect. But, does caffeine –alone– promote weight loss? If that evidence exists, I cannot find it. Every weight loss study I am aware of combines caffeine with something else.
Caffeine has been in MANY products previously reviewed. Just a few include:
In a 2007 mouse study, mice were given a combination of caffeine, arginine, soy and L-carnitine. Researchers noted that while the combination of all ingredients lead to weight loss, neither caffeine alone or L carnitine alone worked.
Mice are not people but this does lend at least some credence that caffeine alone might not work.
While I can understand how a stimulant might help weight loss – by giving people the energy to do more stuff (like exercise) – if caffeine were truly a powerful weight loss agent, then couldn't one get the same effects by using, say, 5 Hour Energy shots ?
Coleus Forskohlii
Also called “Forskolin.” This plant compound is sometimes found in not only weight loss supplements but also testosterone booster supplements too. In spite of its reputation of being a fat burner, there isn't much research on it to say it works or doesn't.
One study of 30 overweight men noted 500 mg of coleus forskohlii given for 3 months 
lead to some weight loss, but this study had problems.
In another study, involving 19 overweight women, 250 mg of coleus forskohlii did not promote weight loss but did seem to reduce the women from gaining weight.
While coleus forskoklii is not technically a stimulant (like caffeine), it might help the production of thyroid hormone. Higher thyroid hormone levels might translate into weight loss.
See the review of coleus forskohlii and weight loss.
Citrus Aurantium
Other names for this compound include “bitter orange,” synephrine, octopamine and seville orange, among others. By whatever name you call it, it's an extract of an orange peel. Citrus aurantium contains a stimulant called synephrine.
Because synephrine “looks” like ephedra, it used to be touted in “ephedra free” weight loss supplements.”
Ephedra is an herb that contains ephedrine, a stimulant that was banned in supplements many years ago due to several deaths. Research on ephedra however did show it promoted some weight loss. Because synephrine looks like ephedra, the hope is that if it looks like ephedra, it might work like ephedra too, without harmful side effects.
Because it is a stimulant, this is one of the ingredients that likely is behind the “phen” part of Phen375 name.
Citrus aurantium contains other stimulants besides synephrine. I'm mentioning synephrine here because it tends to be the most popular of of the ingredients.
There have been studies on the weight loss effects of citrus Aurantium. Back in a 2004 review, researchers found only 1 properly done study that noted no weight loss from citrus Aurantium.
In a 2012 review of previous studies, the researchers noted modest improvements in weight loss when bitter orange was given for 12 weeks. All the researchers in this review, however, had been paid consultants of a company that sold bitter orange supplements.
One problem with citrus Aurantium research is that much of it combines this compound with other stuff (caffeine, green tea, etc.).
For example, in this 1999 review, researchers combined citrus Aurantium with caffeine St. Johns Wort. Combining it with other things, makes it difficult to know how much citrus Aurantium – alone– might help weight loss.
Another issue with research is that there are different types of citrus Aurantium. Some studies might not identify the type used.
Cayenne Pepper
Some weight loss supplements might contain cayenne pepper (or its ingredient, 
capsaicin) in the hopes this spice will raise metabolism. Higher metabolisms might mean more calories burned. At least one study has noted that capsaicin might increase fat burning in those who exercise.
Dendrobium Nobile Extract
Other names that sometimes shows up for this are Shi Hu and Seokgok. Dendrobium (den-drow-bee-um) is a flower, specifically an orchard. Like all plants, there are many varieties (species) and this is no different. According to Orchid.com.uk there are over 1000, different species of dendrobium. Nobile Dendrobium is one of them.
Dendrobium started showing up in supplements a few years ago as a possible replacement for DMAA, a drug that may have been linked to some deaths. In some circles, dendrobium has even been billed as the “DMAA replacement.”
This is because it's rumored that dendrobium contains amphetamine/stimulant-like ingredients such as PEA (phenyl-ethyl-amine).
One problem though with this rumor is that I'm not aware of any stimulant-like ingredients in dendrobium.
One study conducted in 2013, published in the Journal of Analytical Toxicology, that looked into this did find PEA stimulant ingredients in dendrobium supplements (like the CRAZE supplement) but they did not address the issue as to whether these ingredients are naturally occurring or not.
Unfortunately, sometimes supplements might be spiked with drugs to boost their effects. This is illegal and is one of the main reasons why I recommend only dealing with companies you trust.
Dendrobium is sometimes found in exercise supplements although there is little research on it for this purpose. In this 2012 study, a dendrobium supplement did not improve exercise performance or fat loss when it was used for 6 weeks.
One issue with using “extracts” in supplements, in general, is that companies often don't tell us which extract is being used. This makes researching extracts challenging. Regardless, dendrobium is the final ingredient listed in the proprietary blend so it probably is present the least.
Stimulants in Phen375
Looking at the ingredients in this product I feel these are the compounds that act as stimulants:
- Caffeine
- Citrus aurantium
I did not list dendrobium in this list because I can't find good proof that it has any stimulant effects.
Ingredients With Weight Loss Evidence
As far as I can tell, the only ingredient in Phen375 that has weight loss research is:
- L Carnitine
I came to this conclusion because there is research on L carnitine – by itself (not combined with anything else). While I'd like to see more studies done, those studies do exist.
To be fair, one might also add coleus forskoklii to this list because it might reduce the odds of gaining weight (but not promote weight loss).
I did not list any other ingredients because I'm not aware of any goof proof that they – by themselves – help people lose weight.
Of course, it's quite possible all of the ingredients in Phen375 work together to promote more weight loss. The idea behind the ingredients does make some sense. But that will take clinical research to know for sure.
Who Makes Phen375?
While the product website says that Phen375 is “made in USA,” the company behind this weight loss supplement is actually based in Scotland. The company's name is “Shippista LTD.”A derivation of this name may be “Shipit SA.”
Shippista is located at Fountain Business Centre, Ellis Street, Coatbridge, Lanarkshire, ML5 3AA. The Phen 375 website was registered in 2008.
The Better Business Bureau (BBB) lists their US address as 3636 N. Buckner Blvd Dallas, Texas, USA 75228-5610. The BBB gave Phen375 a rating of “F” when this review was updated. See the BBB file for updates and more information.
How To Contact Phen375
The product website lists these contact numbers:
- US phone number: 855-281-8098
- International contact number:214-446-0158
Another phone number for Shippsista is 0-1236-490-065.
How Much Is Phen375?
When this review was created, the product website listed these prices:
- 1 bottle $69.95 (plus $10 shipping/handling)
- 2 bottles $89.95 (free shipping)
- Buy 2 bottles, get one free: $131.90 (plus $10 shipping and handling)
- Buy 4 bottles, get one free $187.95 (plus $10 shipping/handling)
Prices /offers may be different by the time you read this.
Can You Get Phen375 In Stores?
The supplement was only available on the Phen375.com website. It was not sold at local stores like GNC, Walgreens, etc. it may or may not be on Amazon by the time you see this.
Phen375 Money Back Guarantee
The Phen375 website says that if you don't lose any weight after 30 days you can request a refund.
Here is what you have to do to get a refund:
1. You have to download one of the “Phen 375 Official Authorized Diet Plans” from the product website. You have to use one of these diets. When I checked their website, there were 9 different diet plans one could pick from. While I didn't look at these diets, my guess is they are probably either low calorie or low in carbs (either of which will promote weight loss in most people).
2. You have to follow the diet you pick and keep track of your progress.
3. You have to log your starting weight on the Phen375 website.
4. After using the product for 30 days you have to log your ending weight on the Phen375 website.
5. If you have not lost any weight after 30 days, you have to go to your doctor and get a written statement that you, in fact, did not lose any weight!
If you do not get “a reliable certified statement” your doctor proving you did not lose weight, then you don't get your money back. My guess is people do not get refunds on money spent on co-pays when they see their doctor.
Also, you have to request a refund 15 days AFTER the 30 days of using the product to try to be eligible for the guarantee. The 45 days start when you order the product – not when you receive it in the mail.
All of this is laid on on the guarantee page of the product website (Phen375.com/en/guarantee).
How Much Should You Take?
I was informed its recommended that people take 1 tablet per day. That said, I feel it's best to start new supplements with less than is recommended. This is just to see if there are any side effects.
Because this product contains stimulants, I would cut a tablet in half for the first week and only take that a couple of times a week for the first week. When it comes to stimulants, I'll always advocate being conservative.
Phen375 Side Effects
While I think most people might not have issues with this supplement, here is a shortlist of things to consider. This list is not complete:
- Start with less than recommended for the first week to see how you respond
- Talk to your doctor if you have health problems such as but not limited to heart disease, high blood pressure, history/risk of stroke, heart rhythm problems, kidney problems, diabetes, eye problems (glaucoma) prostate problems (BPH), depression/bipolar issues or taking medications for depression and hypothyroidism or hyperthyroidism.
- Talk to your doctor first if pregnant or breastfeeding
- Top at least two weeks before having surgery
- Not intended for those with eating disorders
- Don't take Phen375 or other stimulants close to bedtime
- Avoid if sensitive to caffeine or other stimulants
When in doubt, show the ingredients to your doctor. Pharmacists and dietitians are also very good sources of information too.
Does It Work?
When it comes to weight loss, just taking a pill is usually not the answer. The supplement website clearly states you also have to follow one of exercise and eat fewer calories too. That alone may give you an idea of how effective it might be.
Here's a list of weight loss supplements with evidence.
In my experience this type of supplement is a waste of time and money. It doesn’t put a dent in people with significant obesity or metabolic problems. I know of some supplements that seem to be helpful but most of them focus on improving brain function.
In my experience the majority of obese patients have some degree of food induced brain dysfunction that helps to drive their obesity. They end up craving the highly processed food that is frying their brain. Supplements can be helpful in suppressing these cravings and other symptoms but you need to know how to take them and working on your own this is unlikely to happen for most folks.