Hopefully, you’ve read our last article on a healthy period. If you’re unsure of what happens throughout your menstrual cycle, I highly recommend you read that before continuing on so the rest of this makes sense.

Why might our nutrition needs change with our menstrual cycle?

The key reproductive hormones (progesterone and oestrogen) have myriad roles within our bodies, both contributing in different ways to our feelings of hunger and satiety.

Progesterone stimulates our appetite – it increases hunger.  Progesterone is highest during our luteal phase. Whilst energy intake appears to be lowest around ovulation (REFERENCE), we tend to see our highest calorie intake during the PMS phase (REFERENCE).

Oestrogen on the other hand, has the opposite effect on our appetite. Estradiol, one of the oestrogens that has the largest role in appetite helps us feel more satiated after a meal. Oestrogen also down-regulates ghrelin (a hormone that increases feelings of hunger) and increases the potency of cholecystokinin (CCK: a hormone that increases feelings of fullness). Oestrogen is highest in the follicular phase, dropping during PMS.

Also, many of us experience shifts in sleep onset, quality and quantity during the luteal phase. This can increase the hunger hormone ghrelin, and as a result leave us feeling hungrier than usual.

Ok so we might feel hungrier, what about our actual energy needs?

You may have heard that your basal metabolic rate (BMR) increases during PMS, and that may be correct.  Original research back in the 1980’s suggested a possible 8-16% increase in BMR during the luteal phase (REFERENCE). This equates to about 200 or so calories in the days preceding our period. When left to their own devices, people appear to naturally align their energy intake to their needs (REFERENCE).

The problem is, that was in the early 90s, almost 30 years ago. During that 30 years, we’ve been inundated with diet culture such that most of us don’t know how to honour our bodies needs anymore. We’re tracking, restricting, dieting, overeating, controlling in some way, shape or form, the idea of ‘naturally aligning’ to our needs sounds pretty foreign for many.

It does appear from the research we have available that there is a small increase in resting metabolic rate in the luteal phase (REFERENCE). However, if we group the research we have chronologically, what’s interesting is that in more recent studies published since 2000, there isn’t actually significant difference in metabolic rate at different phases of the menstrual cycle.

What does all of this actually mean?

We may experience a slight increase in energy requirements in the luteal phase. The specific amount by which this happens isn’t certain, and it probably doesn’t matter. Remember, food labels alone can vary up to 20% around their stated energy content according to the FDA. A few hundred calories for a few days might be a natural variation in intake for some.

What does often happen though, and why this is really important, is that you so often ignore it. You spend 5 days asking, ‘why am I so hungry?’ whilst trying to eat your usual foods, then find yourself mindlessly overeating at night because you’re ravenous. If you accepted that your hunger and metabolic needs may be slightly higher, maybe you’d give yourself permission to eat in accordance with that, feel more energised, less ravenous and be less likely to mindlessly overeat later in the day.

Do we need to change the types of foods we eat?

During the luteal phase, we see a slight shift in how we use the foods we eat (what fuels our body uses for metabolic processes). There’s a slight degree of insulin resistance during the luteal phase and fat oxidation is slightly increased (this doesn’t mean we’re using more body fat, simply that fat becomes slightly more preferential to use as energy). This is why you’ll see many people online suggesting you need to eat high carb early in the month and high fat during PMS.

There was one study back in 2016 that investigated the impact of having higher carb diets during the follicular phase (where we are slightly more insulin sensitive) and a higher fat diet during the luteal phase. They found a greater loss of body fat when nutrition was periodised to metabolic changes. However, there were some pretty obvious flaws in this study: protein wasn’t matched between groups; there was a very large drop out rate; the carb differences were minimal between groups. Nobody has replicated this research more robustly since then. There isn’t a single piece of evidence that shows periodising nutrition to metabolic changes is helpful for any outcome: fat loss; health; symptoms; mood etc.

It’s not just the physiological effects of our hormones.

Let’s be honest. Many of us feel somewhat emotionally challenged during PMS. Our mood can fluctuate, our ability to respond not react is tested, and we may find it more difficult to regulate our emotions adequately. Indeed, fluctuations in our appetite, cravings and energy intake throughout our cycle may occur in parallel with cyclical rhythms in serotonin, which can accompany these changes in mood. When we eat foods high in fat and sugar, receptors in our gut respond by triggering the release of dopamine in our brain (ideal for when we feel like crap). Our cravings for foods high in carbohydrates and fat may increase because of these shifts in our affect, as well as some of the hormone-induced metabolic shifts.

You’re probably going to feel better if you give yourself unconditional permission to eat these foods, mindfully. This will, however, be a challenge if you restrict them throughout the rest of the month. If you struggle with eating a few squares of chocolate or one dessert, listen to this episode of the ETPHD team podcast on unconditional permission to eat.

Something to remember

The research available into changes over the menstrual cycle is limited. A large risk of bias is repeatedly cited, as are small sample sizes and large variabilities both between and within people. We don’t have any sort of robust body of evidence that suggests one specific and universal outcome. Please stop listening to people who make money from overcomplicating it in their books and on their social media channels.

A note on oral contraceptives (OC)

Contraceptives may impact energy balance, but we have very few studies in this area (shockingly). To my knowledge, there are only 7 studies (all of which are cross-sectional, which are fine but not super high on the hierarchy of evidence) comparing energy requirements of those on OC vs. naturally menstruating people. Most of them (5) found no difference in BMR in women taking OC. We’ve also no research to suggest differences in fuel use or cravings with OC.

One exception is that of the depot shot. One study observed that 36 months of depot medroxyprogesterone acetate use significantly increased weight compared to women using a combined OC or non-hormonal forms of contraception. But again this is one study. Progesterone only contraceptives are offered to people that can’t take oestrogen for specific medical reasons.

Ultimately no study has clearly shown an effect of OC on weight management - hunger and energy intake.

My recommendations

Get to know your own body.

You might find overcomplicating it makes you feel good. Gosh, there are 100s of people out there making big money on overcomplicating it for you. The reasons that you free great with it are myriad: you’re taking ownership of your health, it feels empowering; you’re probably shifting your nutrition and movement to a more healthful way of things by-proxy; you feel heard as a person who menstruates. But it’s not because you ate slightly fewer carbs during the luteal phase.

If you’re working on your relationship with food, get curious about the changes you notice and begin to honour your hunger and fullness.

If you’re dieting, you might want to increase your targets for the week before your period, by a few hundred or up to maintenance. Or you may not notice anything at all, or may not want to make these changes (which is fine, provided you’re not overeating as a result).  

Do all the usual things to help satiety: eat sufficiently and regularly; eat 3-4 protein servings per day; consume at least 30g fibre; eat mindfully; stay hydrated; be mindful of your consumption of ultra-processed foods.

Love this?

I teach all of this in more detail on EIQ Nutrition, for personal trainers looking to upskill their knowledge with practical evidence-based nutrition, or anyone looking to simply learn for themselves.