One of the most popular tools natural health practitioners and personal trainers use to help speed up weight loss is something called “carb cycling.” Carb cycling and weight loss have an interesting semi-complex relationship that we will disassemble below.
Carb cycling is where you alternate periods of low and higher carbohydrate content in your diet. This means you might spend five days eating low carb, and then eat more moderate carbohydrate for two days on the weekend.
The theory behind carb cycling and weight loss is that it optimizes your body’s metabolic needs. So the theory goes, while in a low carb period, your body sharpens insulin sensitivity, produces glucagon to help you burn fat, and becomes metabolically streamlined. These are great things. Yet if you persist in being too low carb for too long your thyroid hormone levels will drop, and your insulin sensitivity may actually worsen. In short: you may gain weight.
So advocates of carb cycling say that the best thing you can do for your health and waistline is eat low carb most of the time, but still be deliberate about including carbohydrates every so often.
Honestly, I personally don’t do carb cycling in any serious manner (though I do pay attention to the science I describe to you below), and I don’t recommend it for everybody. (Here are some great fat burning tips I do recommend for everybody).
For a lot of women I work with, it is important to consistently eat carbohydrates.
What women benefit from eating carbohydrates?
- They are essential for women who have delicate hormonal systems
- who are recovering from hypothalamic amenorrhea
- who may have thyroid issues
- who are pregnant, nursing, or trying to conceive
- and who have mood issues
Nevertheless, carb cycling is a real, effective tool for fitness and weight loss when used correctly. The problem is that it is not always used correctly. Here’s why, and what to do about it.
1) Carb cycling and weight loss: it’s not gender-neutral
The #1 mistake I see people making with carb cycling and weight loss is inattention to the specific needs of the female body. The idea of carb cycling comes from fitness gyms and online forums (and some scientific studies, though not too many). It is a rather “bro-y” concept.
Because it comes from a world of men, it doesn’t pay a whole lot of good attention to women. But there are two important considerations to bear in mind:
A) Thyroid status must be protected.
Thyroid hormone is essential for fat loss. Unfortunately on a low carbohydrate diet thyroid hormone production can slow down. This is crucial to bear in mind for women especially because women’s metabolism and thyroid activity are much more sensitive than men’s. It is important in the “low carb” times of the cycle to still not be very low carb. Stay above 50 grams of carbohydrate a day, at very minimum (and higher if physically active).
(Check out these documents for more on how to protect your thyroid while losing weight.)
B) Female hormones impact insulin sensitivity
Estrogen and progesterone have significant impacts on carbohydrate metabolism. At different parts in the menstrual cycle, carbohydrates are processed either much more efficiently or with much more fat storage. This is the secret to female carbohydrate cycling. Instead of sticking to a simple regimen provided by a personal trainer or some internet forum, the best thing you can do to maximize the effectiveness of your carb cycling is sync it up with your menstrual cycle.
2) Carb cycling and weight loss: when to eat more carbs
There are two important facts here: estrogen slightly increases, and progesterone decreases insulin sensitivity.
Estrogen and progesterone are elevated at different points in the menstrual cycle. Estrogen levels tend to be the most dominant in the first and second weeks of the cycle (especially the second week). Progesterone levels are at their highest in the third and fourth week of the cycle.
The consequences of this are that:
- The female body is naturally more insulin-sensitive in the follicular phase (the first two weeks of the cycle) when estrogen levels are highest and progesterone levels are at their lowest. This means it tolerates carbohydrates in these two weeks better than the rest of the time.
- The female body is naturally slightly less insulin sensitive when progesterone levels are higher in the luteal phase (after ovulation, in the last two weeks of the cycle). This means it does not tolerate carbohydrate as well in these weeks. Women who are diabetic know this well. I’ve read many studies and heard from many women I know that their insulin injections have to increase in the second half of their cycle because their blood sugar levels are inordinately high.
3) Carb cycling and weight loss: what to do about it
I have talked with fitness professionals like Luke Robinson of Wolf Pack Fitness fame at length about the diet and exercise recommendations they make for women who carb cycle.
They usually recommend that their clients reduce carbohydrate intake in the final two weeks of the cycle, in the luteal phase, when insulin sensitivity is at its lowest. This means that in the first two weeks of the cycle carbohydrate intake might be completely ad libidum or whatever-you-feel-like. That may be too vague for you!
If you want a hard and fast number to adhere to, maybe 35 percent of calories or 200 grams of carbohydrate a day is a good place to start. It can be at its absolute highest in the second week of your cycle, around 45% of calories.
This number varies based on how much you exercise, of course. The more you exercise, the higher that number can be.
In the second two weeks of the cycle, when insulin sensitivity is at its lowest, carbohydrate intake should drop to about 100 grams of carbohydrate a day, which is approximately half of what their clients were doing previously.
The actual numbers are less important to pay attention to than the ratios: insulin sensitivity and weight loss are maximized when carb intake is cut in half in the second half of the cycle.
It is also important to note that I recommend carb levels do not drop below 100 grams a day. That is my preferred number for a lower limit for women, so as to prevent fertility and thyroid problems.
You can find out more about what I recommend for carbs, weight loss, and other paleo tricks, in my extensive book on weight loss for women, Weight Loss Unlocked.
4) Carb cycling and weight loss: fitness recommendations
Fitness gurus also recommend a corresponding shift in type of exercise.
Since insulin sensitivity is at its highest in the first two weeks of the menstrual cycle, and carb intake is free to be at its highest, exercise can be more aerobic (long, moderate heart-rate-elevating cardio exercises). It is at this time that you can do your best high performance cardio training. Here you can challenge yourself with longer-term exercises that may be more “stressful” for your body, like long bike rides, tabata sprints, night-long dance sessions, and the like. It is at this time in your cycle that your body can handle the most aerobic stress.
Since insulin sensitivity is at its lowest in the final two weeks of the cycle, and carb intake is also at its lowest, exercise should be more anaerobic (this means hard and fast, really getting your heart pumping). It should be focused more on high-intensity interval training, with short bursts of high intensity work, either from brief sprint exercises or from weight lifting. This is an excellent way to sharpen insulin sensitivity while simultaneously burning fat, increasing muscle mass, and spending calories. It also helps the body stay healthy and as stress-free as possible during this time in which the body is gearing up to menstruate and the least capable of handling stress.
5) Carb cycling and weight loss: the bottom line
I always refrain from providing any hacks or tips I might recommend to shed the “last ten pounds” or what-have-you. I find most of these tips to be unhealthy and antagonistic to healthy weight maintenance in the long-run. Yet even more importantly, I do not want to open doors to you that lead down winding corridors of obsession with weight loss and body image. I know how terrible it is to walk those corridors. I don’t want to be a part of encouraging anyone to do it. In some ways, I consider it my moral duty to refrain from ever facilitating obsession with appearances.
But carb cycling is a nice bit this is one piece of advice I know is solid, and one that I believe can be used responsibly for the sake of how good you feel, how athletic you can be, and also how fit and slim you are. I believe the most important part of your goals for weight loss should be health. Used responsibly this advice can be great for your health, while also—if done so, again, responsibly and with patience and room for less-than-perfect compliance—can be used to keep unwanted insulin weight off your body.
Finally, for more on my unique thoughts on carbohydrates and weight loss for women specifically, check out my program for weight loss, Weight Loss Unlocked! You can read all about it here.
Do you have experience with carb cycling and weight loss, especially with your cycle? How do your hormones affect your diet and fitness?
Note - some links above may contain affiliate links. You don't pay more, but we get a small cut to help keep this organization running. It's tough to balance ethics with the need to stay alive. Thank you for your patience and understanding!
.
When you write about grams of carbs per day, do you mean total (including fiber) or net (subtracting fiber)?
Since my carb recommendations are on the high end I like to include fiber. Good question 🙂
What are your recommendations for those of us who are post-menopausal?
GREAT QUESTION. You don’t have to worry about a cycle. Of course it varies woman to woman, but after menopause i think it’s probably totally healthy to carb cycle the ‘normal’ way – that is, to do some days on and some days off, however many of course works best for you.
Thank you so much for this article on carb cycling & weight loss for women! I found it tremendously helpful for personal reasons but also because I work with so many women (as a personal trainer) who encounter significant frustration when it comes to weight loss, health & hormonal status (the interplay among them). Your article seems to speak to mostly women of reproductive age or to women who are still menstruating. I also work with many women age 50+ and wondered what recommendations, if any, might you have to offer regarding carbs/carb cycling for peri-/menopausal/post-menopausal women? Thank you so much, Stefani – the info & wisdom you share on your blog & via your podcast (which I love!) are invaluable to me. I also totally dig your book and recommend it to other women all the time! I so appreciate the work you’re doing!
Great information, thank you! I’ve noticed I do in fact intuitively crave carb re-feeds during that second week in my cycle, though hadn’t really pinpointed that detail till I thought about it. And it does in fact seem to help my body perform and feel lean. Don’t you just love body wisdom? 🙂
YES I DO!
This is good information for women who currently still have a normal cycle. I’m 45 and although I am not currently in menopause, I have to take birth control pills to supplement my hormone levels. I am also 40 pounds over weight and struggling to find the right solution to lose this weight. How would carb cycling work for someone in my situation?
If you are on the birth control pill, it depends on which one. Some pills are just progesterone. if that’s the case then your insulin sensitivity may be a BIT hampered. If you have a progesterone/estrogen combination pill then its a bit less easy to tell how you may be experiencing hormone fluctuations and which is more dominant in you. If they are well balanced then I wouldn’t worry too much about taking care of them and would consider cycling the ‘normal’ way
I love the idea of carb cycling and I tried it in the spring when I bought weight loss unlocked. With my Hashimoto’s condition, though, I really suffered during the low carb part of the cycle. I might try it again, and just do a lower carb diet during my last two weeks, but still keep it at 100-150g per day. It’s always a work in progress. Thanks for shedding more light on this!
hi there! i found your site at a link from ben greenfield and love it! im confused because i read a post on his site about exercise and menstrual cycle and it said that the follicular phase is best for anaerobic work and luteal for aerobic which is the opposite of what you recommend. i guess i thought that hi intensity workouts rely more heavily on glycogen and wouldnt be done in a lower carb time. not challenging you, just truly curious what you think? thanks!
Excellent question! I suppose you could look at it like this: you are less insulin sensitive in the luteal phase, so in order to prevent fat gain it is “more important” to burn sugar and fat at this time – so if weight loss is your goal, and if you do good, hard anaerobic workouts, then this will sharpen your insulin sensitivity as much as possible and help keep you lean via that mechanism. If, on the other hand, weight loss is not your goal but fitness and strength are, then you may wish to do aerobic work at this time (with higher blood sugar you can accomplish greater aerobic feats), and save the anaerobic work for the rest of your cycle. Does that make sense? At least, that is what I am guessing is happening here.
Hi Stefani, I would like to ask your opinion. I’m eating an average 90-100g protein, about 100-120g carbs and about 60g fat a day. It usually comes out to be around 1200-1400 calories. I just simply can not eat any more a day. What do you think is better? To get enough highly nutritious but low calorie food or higher calories less nutritious food. Thank you very much in advance
Um, more of both, why can’t you eat any more a day?
Where do fats factor in for the follicular phase and the luteal?
Fat doesn’t have much of an impact on the insulin response so it’s effect remains neutral throughout the menstrual cycle 🙂 If you decrease carbs in the latter half of your cycle however you may wish to reduce the fat content to stay in energy balance
Dear Stefani, I am 65 years old and I would like to ask, what is your advice for post-menopausal women in regard to carbo-cycling? For the past 8 months I have practiced IF (fasting nearly daily, between 16 and 24 hours) combined with carbo-cycling (extremely low carbs for 3 or 4 days in a row followed by 1 day of carb reloading) to dramatically reduce my calorie intake while eating nutritious foods only. As a result, I have lost 70 pounds. Now that I am at a good weight and feeling well (I exercise daily), I would like to think I can use IF and carbo-cycling when necessary to avoid regaining weight. But I am concerned by the possibility that I may actually be undermining my body’s insulin sensitivity.
If it’s working for you I wouldn’t worry. I think health problems with low carb are slightly less of a concern in later years simply because there aren’t any hormones around to mess up. 🙂 I would simply be very cognizant of potential changes or symptoms – and if you start to notice weight gain, thyroid symptoms, etc while IF/carb cycling then it might mean it’s time to simply lighten up the IF and add in a few more carbs. you don’t need to eat HIGH carb but some relaxation of your guidelines, or playing with them a little bit, could be called for eventually (or now if you so choose) 🙂
excellent article, you are nice and clear, as well as being wellxspoken. thank you very much for taking the time to write this
I am 55 and have been in menopause for 5-6 years, I also had my thyroid removed at 31, So I have a lot of trouble keeping weight off, never mind losing some. I am taking thyroid hormone as well as estrogen and progesterone. What is the best way for me to carb cycle? I feel like you are saying that I should be careful about going to low carb when carb cycling. So keto would be out then, I guess?
I think it’s all right to try keto especially since you’re past your reproductive years. Just keep an eye out for any symptoms that crop up 🙂
Can you help me figure out when I am supposed to do high carb days and low carb days? I’m very confused about this program but really want to try it. I am 42, 5’1″ and 160. I work out 3 times a week. I am pre-menopausal. My goal is to loose weight. Thank you for any help and advise!!!!
Hello I have suffered from hypothalmuc ammenorhrea since my early teens and I never had a natural period. Unexplained condition where my pituary and hypothalamus did not communicate. I was not underweight. I was put on birth control to prevent bone loss since I do not produce estrogen. I had a child through IVf 2 years ago and I am back on birth control. Marvelon and combo estrogen and progesterone. I am able to follow this plan? I am at a plateau with my weight loss since starting the pill
Yes you are <3
Hello
Thank you so much for this. I always do fine on any diet until 2 weeks before my period. I become very huNgry and want to eat eVerythig in sight and carbs are my friend during that time. All i want is carbs. Then once i get my period im fine for the next 2 weeks after that. im so sick of my period ruining my weightloss efforts so this article has been a godsend. However it seem that you are saying the opposite of what I have been thinking. I become so ravenous for carbs during the 2 weeks leading up to my period that i assumed while reading this article that i should be have more carbs d but it seems that you are saying I should have less. And the period i feel more in control, the 2 weeks after my period when i could literally adhere to any diet, thats when i should have more carbs?
Is this correct?
well, you might be craving carbs at this time (in the final two weeks) because you’re going through more blood sugar swings due to the lower quality insulin regulation. it’s a possible explanation, in any case <3
In terms of the 4 week cycle.. The first 2 weeks when you eat the most carbs, is this the the 2 weeks after your period or prior to your period?
the week during and after your period 🙂
Hi! I have a few questions.
I am mid 40s and already going through perimenopause phase sinc last year. Seems like I gained suddenly body fat even exercise with HIIT, cardio and weight lifting. I eat clean, no sugar, no flour and processed food. I assume it is to do with my hormone change. I have light period and shorter now these days. Still experiencing mood swings, breast tenderness, bloating and weight gain, hungry for sweets and salty before period. I try to find any articles about carb cycling for women who go through perimenopause phase but can’t find them.
Can you tell me what I can do for carb cycling when I go through this horrible hormone changes and still try to lose body fat and weight?
have you read any of dr sara gottfried’s work? She is actually quite smart and specializes in the challenges of menopause and perimenopause <3
Hi Stephani,
Would it be safe for the thyroid to carb cycle every other day, with the low day being 50g and the high day being 100+g? I would think that as long as you are not doing too may low days in a row, or for a long term period, that it would be okay for they thyroid to do this type of cycling.
Yeah I think so, especially if you just monitor yourself! 🙂