Why You’re Not Losing Weight With Phentermine

Why You're Not Losing Weight With Phentermine

Phentermine is undoubtedly an extremely effective weight loss medication.

Still, for all of those who experience weight loss success, some are left wondering why they’re not losing weight with phentermine.

While it could be that phentermine has stopped working for you, if you can still feel the effects of appetite suppression and added energy, then it could be for one of these reasons.

1. Eating Too Much

Counting calories can be a pain, but it’s a good way to know how much food you can have at each meal and for each snack.

In addition, it’s also important to weigh your portions as you could be overestimating how much you’re meant to eat of certain foods.

Test how accurate your judgment is by portioning your food as you normally would and then weighing it out afterward.

If you’re consistently serving yourself generous portions, then you could be consuming A LOT more than you think, therefore making losing weight with phentermine more difficult.

2. Not Eating Enough

Phentermine works by suppressing appetite, but sometimes this effect can be too strong, to the extent that people have zero appetites and can struggle to eat anything all day.

You may think that less food = more weight loss, but as we explain here.

That’s really not the case; there is an ideal amount of calories that you should be eating to successfully lose weight, and getting that balance right is the key to losing weight with phentermine.

If you’re consuming too few calories each day, your body’s reaction is to think that there are lean times ahead, meaning that it will turn your metabolism right down and cling onto any fat that comes its way, i.e., you are less likely to lose weight.

3. Not Getting Enough Sleep

Establishing a healthy diet and becoming more active will help you to shed pounds.

Still, lifestyle factors such as getting enough sleep also play an important part in your ability to lose weight with phentermine.

When we lack sleep, our brains crave unhealthy easy foods, and our hormones tell us that we’re hungry when we’re not.

This is clearly not a recipe for losing weight with phentermine, so make sure to prioritize sleep and get at least 7 hours every night.

4. An Undiagnosed Health Issue

Before prescribing phentermine, your doctor should check that you aren’t suffering from one of the many health issues that can cause weight gain or make it difficult to lose weight.

These health issues can include a vitamin or mineral deficiency, such as anemia, Polycystic Ovary Syndrome (PCOS), diabetes, or an under-active thyroid, among others.

If you haven’t been fully checked for these types of issues and losing weight with phentermine is proving to be difficult, then ask your doctor for a full health check-up, even if just to eliminate these potential reasons.

5. Not Getting Your Vitamins

Deficiencies in vitamins and minerals lead to a sluggish metabolism and slow bodily processes, meaning your body has to work extra hard to process the food you eat.

As a result, losing weight with phentermine is more difficult. So, ensure you get the recommended daily requirements of important weight loss nutrients for better results.


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6. Too Stressed

Stress can be one of the underlying reasons for weight gain, so it makes sense that it’s something that needs to be addressed to lose weight.

One study found that participants taught stress-management techniques were able to lose significantly more weight than the participants who weren’t taught these techniques, even though their diets and activity levels were the same. 

Reducing stress balances out hormones and allows your body to function better, so you should aim to reduce your stress levels for success in losing weight with phentermine.

Click here for some great ideas on how to manage stress.

7. Not Exercising

Many people rely solely on diet to lose weight, which can be effective to a certain extent, but it’s the combination of diet and exercise that really gets results.

Unless you cannot exercise due to injury, you should get moving every day, even if it’s just walking for half an hour.

If you find it hard to get motivated to exercise, check out these ways to make exercise more fun.

Exercise is a great stress reliever, and adds to your phentermine energy boost, and research into long-term weight loss has consistently found that exercise is the key to losing weight with phentermine for good.

8. Eating Too Many Empty Calories

Losing weight with phentermine isn’t all about eating less; it’s more about eating better.

And the same is true of your calorie allowance; just because two foods have the same amount of calories does not make them equally good for you.

Furthermore, low-calorie or low-fat options aren’t always the way to go, so try to avoid light, low-fat, or specific diet foods as they often substitute healthy fats or calories for added sugar or salt and can be more processed than the regular foods they aim to replace.

Instead, aim to get the best from your diet by seeking out foods packed with vitamins, minerals, and healthy fats, avoiding anything overly processed and filling up fiber and protein to keep hunger at bay for longer.

You should also watch the calories and sugar you consume in your drinks, as liquid calories can really add up without giving us any value for money as far as goodness goes.

9. Not Drinking Enough Water

Drinking water has so many benefits for those losing weight with phentermine.

Water suppresses your appetite by filling you up without the calories, it helps your body work better and boosts metabolism, maximizes the effects of phentermine, relieves side effects, and it helps you drop water weight.

Make water the ONLY thing you drink, and you’ll be sure to see a reduction in side effects, a healthier you, and improved weight loss results.

And, for an extra weight loss boost, add the ultimate detox, Phen Drink, to water to see even more success.

10. Not Challenging Yourself

If you’re starting from zero, then phentermine will give you a huge burst at first.

Still, too many people continue on automatic pilot and expect to see these great results all throughout their phentermine prescription.

Instead, you should see it as a learning process, where you expect to progress and improve in all aspects of your life, and not just as a means to an end.

So, challenge yourself continuously to eat better and be more active by setting new targets and mini-goals to keep your interest up, and you’ll be sure to enjoy more success losing weight with phentermine.

Could one of these reasons be why you’re not losing weight with phentermine? Let us know by commenting below!

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  1. I just started using phentermine and I don’t have mood problem. I’m still have and appetite I exercise before I go to work.I eat breakfast lunch and dinner. One thingi notice is im very tired. I mean my metabolism is very low.my questions is can I take and energy drink to boost it.

    1. Hi Jay,
      If you’re tired it could be a side effect of the phentermine. We would advise you to try more natural methods to increase energy first, such as drinking water, sleeping at least 7 hours each night, and continuing with the exercise as this will help to increase energy levels. We would not recommend that you drink energy drinks as these are made up of chemicals and sugar, both of which will make phentermine less effective and will not help your weight loss efforts either. If your lack of energy continues then you could try the weight loss supplement Phen Caps which we recommend for added energy and appetite suppression to boost your phentermine. Here is a link to find out more: https://www.phen.com/
      Hope that helps!
      Sally, phentermine.com

  2. I’m taking Phentermine 37.5 mg. For almost 2 months now I started last month & I have not felt anything no weight loss, I have had the gastric by pass surgery done, I really can’t do any exercises, my knees prevent me I have severe arthritis in my left knee but it’s in both knees, I do diet I always buy fish tikapua, frozen veggies, fruits usually bananas, grapes, cantaloupes, honeydew melons, so my question is why am I not losing but gaining it all back, I was on belviq for a month my INS wouldn’t cover it; it’s too expensive for me, so help me out here what am I doing wrong, little today bit I do lack sleep I’m Lucky to get at least 3-4 hrs of sleep; I chew ice cubs cause I retain fluids

    1. Hi Donna,
      The lack of sleep could be a factor, and retaining fluids would mean that you’re less likely to see a drop on the scale even when you have actually lost fat. You could try upper body exercises which would help to build muscle, and swimming is usually a safe exercise even for people with injuries. Do you feel the effects of phentermine, such as a suppressed appetite and more energy? If not then it may not be working for you like it should.
      Sally, phentermine.com

    1. Hi Shelley,
      This is not a typical side effect of phentermine – you should talk to your doctor straight away.
      Sally, phentermine.com

    2. When I started taking them it stopped my period. I researched it and several people had the same thing happen to them.

  3. I’ve been on adipex/phentermine for 2 weeks.. I know not a long time. I have lost 4 pounds.. the problem is, is I keep gaining weight back. I started at 240, I went down to 233, then I’ll gain back 2-3. I eat 1000-1200 calories a day. And I exercise. Could the problem be my thyroid? I am on synthroid and getting half my thyroid removed. Once I get it removed will my weight loss from phentermine get better? I need this to work, I feel like I’m out of options.

    1. Hi, I am having the exact same issue. Is it pointless to take phentermine until your thyroid levels have balanced? I really hope they answer this question.

      1. Hi Shannon,
        This would depend on the individual and what their doctor thinks is best for them. For some people is is more helpful to get their thyroid levels balanced before they start their weight loss journey with phentermine, but for others the whole process works better with help from phentermine to suppress appetite and boost energy while their levels are normalizing. Talk to your doctor about what he or she thinks is best for you.
        Sally, phentermine.com

  4. Hi, I started taking phentermine and am on my 2nd week. I lost 7 pounds but on Monday when I started my 3rd week I gaind 5 pound it just doesn’t makes sense – I exercise 5 days a week and drink 80 ounces of water a day. For breakfast I eat 2 eggs with spinach, for lunch I have a chicken salad, and I hardly ever eat dinner maybe a cereal once in awhile. Can someone tell me what I’m doing wrong I’m so disappointed

    1. That was posted last month, have you lost any yet? I’m in the same boat. I exercise 5 times a week and I eat 1200-1300 calories a day. No weight loss in 2weeks

  5. Only lose 5 lbs a month
    I still feel sluggish during the day and can sleep but can’t sleep at night I’ve been on adipex 2 months – cravings don’t deminish as I am a extreme binge eater of 16 yrs not by choice but by habit. I try to eat three small meals but find myself getting sick so I got stuck 160 weight after kids and can’t get back down 🙁 why isn’t it working for me like it does my friend who is a nurse?

    1. And I am very active I push 5miles every other day drink only water and eat veggies raw yum I love my veggies just thought I add

  6. I started Phentermine on 4-28-2016. So far I’ve lost 18 LBS! I drink half my body weight of water, eat healthy and exercise daily. I burn almost 800 calories every day. I do a lot of the incline on the treadmill and elliptical, even cardio! But I still fit in my same pants size. I started off at 260, to 242. I have two more months left with phentermine..

    1. I also started the same same day 4/28/16 on the first month i lost 16lbs im already on my 3rd month feeling great havent weighed my self though till i go back on August 11th…… 🙂

  7. I started this 8/6/16 weighing in at 223 at the doctors office but then I weighed myself with my own scale on 8/9/16 and weighed 211 so I really don’t know which scale number is correct because it is impossible to lose that much weight in like 2-3 days and I don’t feel the difference, but it’s probably the 223 lbs that I probably weigh, so I probably still weigh the same. Anyways, ever since starting this I’m even hungrier than before starting this pill, I eat a normal meal and then start to get full, but after like a half hour I get really hungry and nauseous, and my stomach feels empty. Today I kind of felt a little dizzy that I thought I was going to pass out, but I didn’t since I rushed to the kitchen to eat something. I also feel weak and sluggish but not tired, and it is really hard to go to sleep at night and go back to sleep because I take this pill at 6 am and then go back to sleep since I normally wake up at 11 am or around noon, but I’ve basically been sleeping for like 3-4 hours ever since. I don’t know but ever since starting this I feel like sh!!!t but very wide awake which I didn’t before because I always felt tired before taking this pill. Maybe I need to lose weight the normal weigh… (haha get it? lol ill stop.)

      1. Sorry forgot to add more…

        I have a gym membership that I haven’t used in months and I would love to go back or at least go to the nearest trail and walk but I’m afraid that I’m gonna pass out since I feel weak-ish and feel heavier and sometimes I feel like my eyes want to go dizzy but I don’t end up stumbling or anything.
        I don’t know, I probably need to stop taking this.

  8. Lost 5lbs first week, one lbs the second week. I’m on my third week but my husband threw my pills away so I’m not on them this week and I feel bloated!! 🙁 my Dr won’t Rx them until next week bc they only allow 7 pills a week. I weighed on my home scale and it looks like I’ve gained back almost all the weight I’ve lost!! 🙁 how and why I don’t know, I sleep enough, I walk a mile every day twice a day, I eat one cup of food per meal as directed by my Dr and only what’s on the plan and have my three snacks which of course is veggies or a fruit, also only approved items on the list and even got my shots to boost energy. I take b12 and b complex and iron for my anemia. What could be wrong that I’m gaining ??? 🙁

    1. Hi!
      The weight gain might be related to the bloating you’re experiencing. It could be related to your menstrual cycle, not drinking enough water, a food intolerance, or if you’re suffering from constipation as a side effect of phentermine. It’s not possible to gain that much weight in a week so it’s more likely to be water weight. If both you and your doctor think that this plan is the best way for you to lose weight then it shouldn’t matter if you are taking phentermine or not – phentermine does not directly cause weight loss, it just helps you to stick to your plan, which you seem to be able to do without phentermine. Just keep doing what you’re doing and stay strong! 😀
      Sally, phentermine.com

  9. I am currently taking phentermine. I still feel the energy but I do feel hungry during the day. Does that mean its stopped working for me?? Also, I weighed myself this morning and weighed in at 164. I got back on the scale when I got home from work and I weighed 165. Why?! I’m taking birth control so maybe that’s interacting with it and causing my weight loss to slow down??

    1. Hi Jessica,
      This is the problem with weighing yourself too often. Your weight increases throughout the day due to the food you’ve consumed, liquid levels in the body, salt etc. You also get shorter throughout the day but then at night your body is still running, using the fuel consumed throughout the day while also stretching out your limbs and muscles, so that you wake up taller and lighter than you were when you went to bed. You should only weigh yourself in the morning before any food or liquid and ideally just once a week as that’s when you notice the overall difference, rather than becoming preoccupied with these ups and downs of a pound or two here and there which happen constantly throughout the day. Contraceptive pills haven’t been found to interact with phentermine so these are unlikely to affect your weight loss. And, with respect to still feeling hungry, only you know if this hunger is more or less than you used to experience. But, it is normal and correct to still feel hungry on phentermine – it isn’t designed to completely remove hunger. These tips on how to suppress appetite should give you some advice about the types of foods which will keep hunger at bay for longer: https://www.phentermine.com/blog/10-tips-suppress-appetite-phentermine/
      Sally, phentermine.com

  10. I am not sure if anyone still uses this blog but I have been on phen since Aug 9th. I have lost 15lbs but over the last week I haven’t lost anything at all. I eat oatmeal for breakfast, yogurt and a fiber one bar for lunch, and usually chicken breast and a veggie for dinner. I am also working out 5 days a week. I cant seem to lose anymore although I am nowhere close to a normal BMI. Is anyone else having this issue?

    1. Hi Shaunte,
      The blog is where we post articles about phentermine and the comments on them are usually questions for us to answer. To connect with other phentermine users for advice and to share experiences, remember to join our Facebook support group!

      In answer to your questions though, I have a couple of suggestions. Firstly, losing 15lbs in less then 3 weeks is really great and something to be celebrated. However, weight loss is not always linear – it is not typical to lose consistently every week, so this stall isn’t permanent, your body just has to adjust itself to take your losses into account. Secondly, it doesn’t sound like you are eating very much. I don’t know if you’ve just outlined a few of the things you eat, but you should be eating at least 1200 calories a day – oatmeal is great for breakfast but adding some fruit would be better, lunch should be around 300 calories and should incorporate some vegetables or legumes for fiber, protein and nutrients, and then your dinner seems fine. The fiber bar and yogurt would work better as snacks, and maybe add some sources of healthy fats to your diet such as oily fish, avocado, nuts or olive oil, as well as more whole grains, such as brown rice, quinoa or whole grain pasta. Hope that helps!

      Sally, phentermine.com

  11. Hi , I was on phentermine 2 years ago for 3 months and lost 30lbs. It suppressed my appetite and worked great. I just started it again one month ago and feel no different taking it (like I did before) & have not lost any weight. Does it just stop working as effectively as it did the first time you introduce it to your body? Nothing with me has changed over the past two years, so it leads me to believe it’s no longer effective.

      1. I lost 47 pounds in three months a year ago on phentermine. Gained it all back and then some because I have multiple herniations in my back that stopped mobility for a long time. I and in the first week of my second month now. The first month back on phentermine I only lost four pounds. I was so disappointed. But now this month I’ve lost 8 pounds in five days. Y’all hand in there. I boostedmy water intake and stayed sweating finally(I’m not a sweater normally)

  12. I have been on phentermine for 4 months. The first 3 months I lost a total of 30 pounds! Yay! This last month and a half I have completely stalled and am at 180 pounds. My doctor and I have discussed my goal weight and we came to the conclusion that 160 is a good weight. I am only 15 pounds away from my goal and don’t know what else to do. I track my daily food and caloric intake and I eat between 1200 and 1350 calories. I have cut out all sugary and caffeinated drinks and only drink water throughout the day. I walk 30 minutes every other day and more on the weekend. I just don’t know what else I can do to jump start my weight loss again.

    1. Hi Rachelle,
      As well as walking it could be beneficial to do weight lifting and also more strenuous cardio such as fast cycling, running, dancing or swimming. Walking is great but it’s counted as NEAT (non-exercise activity thermogenesis) rather than exercise, especially if you’re walking at under 5mph. Plus, as well as counting calories and avoiding sugar, are you making sure you eat plenty of nutritious food, protein, fiber etc? And don’t forget making sure to get enough sleep and reducing stress – weight loss is more than just about diet and exercise.
      Sally, phentermine.com

  13. I’m having a hard time getting my doctor to prescribe Phentermine 37.5 to me here in Florida and I do weigh 154 pds and only 5’2…which typically is very overweight and very common to be able to get it for at least 3 mths. When I lived in Kansas my doctor had no problem prescribing it to me once he checked my blood pressure every month and I still had a little bit to lose. Any recommendations of doctors in Orlando that will prescribe it?

    1. I suggest going through a medical weight loss clinic. I was at 181 at 4″11 and my doctor never suggested it, just said eat healthier and take these anti-depressants so you don’t feel anxious -_-. When I got to 205 I decided enough was enough. I went through a medical weight loss clinic and got the RX. My first round alone I went from 205 to 181.

  14. Hi,
    I started taking phentermine 30 mg on Dec 14th.
    I am eating well, drinking lots of water, taking Multivitamins and probiotics and exercising 3 times a week but have not lost any weight till now. Should I ask my doctor to increase my dosage to 37.5 mg? If anyone faced same issues, please advise what should I do.

    1. I myself am going through the exact same thing I’m on 30 mg I wonder myself if I need a higher dose. I’m working out watching my calorie intake but no effect I started January 24, 2017 and I drink plenty when do you notice results?

  15. I started phentermine in October and in the first month I lost about 15 pounds. I had to stop taking the pills because I was very restless at night time, and to anxious during the night. Since I want to loose 20 more pounds I started them again in January 2017, have not lost a pound, but still can’t sleep at night, feel restless, and constipated. Don’t get very hungry either. Don’t know what to do. Has anyone experience any of this? And suggestions? Thanks

    1. Hello Kariannis, thank you for reaching out. We’re not sure if it’s that phentermine doesn’t have the same effect after you’ve taken it before or if the manufacturers have made changes to it, or maybe both. Some people find it helpful to take additional supplements such as 5-HTP or B12, as both have been found to boost energy and motivation on phentermine. Or you could supplement your phentermine with an alternative like Phen Caps to give yourself an extra boost. If that doesn’t work then perhaps your doctor could suggest something, such as a new brand or seeing if switching from tablets to capsules could help. You can find out more about it here: https://www.phen.com

      You are welcome to join our brand new support group so you can connect with other phentermine users, share your experience and get some valuable advice. https://www.facebook.com/groups/1069871763087734/

      Have a nice day!

      Rebeca, Phentermine.com

  16. Hi my name is Liliana I started phentarmine on January 1-2017 the first month I lost 15 lbs. I am on my second month and haven’t lost a lb. I’m down to 180 been there for almost a month, I work out 5x a week and supplement 2 meals for protein shakes. I don’t know what else to do I feel disappointment since I feel I am doing the diet correctly.

    1. Hi Liliana,
      As the article above explains, there are lots of factors to consider when it comes to weight loss – you may not be eating enough if you are substituting meals for protein shakes, or possibly getting more sleep or focusing on other lifestyle changes could help get your losses moving again. We would advise you to look at your diet and how you can improve it in terms of nutrition, and also to switch up your work out routine to combine weights and cardio if you’re not already doing that.
      Sally, phentermine.com

  17. I’m in the same boat as Lilana. I lost 11 pounds the first month and now two weeks into my second month only one pound. I’m eating about 1000 calories a day, fruit and lots of water included, not too much fat. I’m sleeping fine every night. I really don’t know what else to do. Also exercising at least five times a week. Any advice for me?