Can Eating Too /Little Affect Your Hormones and Fertility?

Eating Less Isn't Always Better: Energy Availability, Hormones & Women's Health

You’ve probably heard it before:

“Eat less and exercise more.”

Or maybe, “You just need to be in a calorie deficit.”

Yes, energy balance matters when it comes to weight loss. But for women, especially during the reproductive years, perimenopause, and menopause, the conversation is much more nuanced than simply cutting calories and exercising harder.

More restriction isn’t always better.

In fact, consistently asking your body to do more while giving it less can affect far more than the number on the scale. It can influence your menstrual cycle, reproductive hormones, bone health, thyroid and metabolic function, recovery, mood, sleep, and overall health.

So, let’s talk about energy availability and why adequate fueling matters so much for women.

What Is Energy Availability?

We often hear terms like basal metabolic rate (BMR), resting metabolic rate (RMR), total daily energy expenditure (TDEE), and calorie deficit used interchangeably, but they don't mean the same thing.

Your BMR or RMR represents approximately how much energy your body requires at rest to maintain essential functions such as breathing, circulation, cellular activity, and organ function.

Your total daily energy expenditure is higher because it also accounts for physical activity and the energy used throughout your day.

Energy availability is another concept altogether. In research, it describes the dietary energy remaining for the body's physiological functions after the energy cost of exercise has been accounted for, relative to fat-free mass.

That distinction matters.

For example, imagine a woman has an estimated resting energy requirement of approximately 1,350 calories per day. That does not mean 1,350 calories is an appropriate weight-loss target. Her actual daily needs may be substantially higher once walking, working, exercising, digesting food, and everyday movement are taken into consideration.

Depending on her activity level, her total daily expenditure could easily be closer to 1,600, 1,800, 2,000 calories—or more.

This is why I don't love blanket recommendations telling women to “just eat 1,200 or 1,500 calories.”

The appropriate intake depends on the individual.

Her body size, body composition, age, activity level, exercise volume, goals, current health, menstrual status, and metabolic demands all matter.

And when energy intake becomes too low relative to what the body is being asked to do, we can begin to see physiological consequences.

Your Brain and Ovaries Are Constantly Communicating

One of the systems that can be affected by inadequate energy availability is the hypothalamic-pituitary-gonadal, or HPG, axis.

Think of this as a communication network between your brain and reproductive system.

The hypothalamus releases gonadotropin-releasing hormone (GnRH), which signals the pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Those hormones then communicate with the ovaries and help regulate ovulation and the production of reproductive hormones, including estrogen and progesterone.

This communication system is sensitive to the body's overall environment.

When the brain perceives inadequate energy availability or significant physiological or psychological stress, GnRH pulsatility can be altered. Downstream LH and FSH signaling may then be affected, potentially disrupting ovulation and menstrual function.

Your reproductive system doesn't operate independently from the rest of your body.

Nutrition, energy availability, exercise, sleep, stress, and metabolic health are all part of the conversation.

When Your Period Disappears

One potential consequence is functional hypothalamic amenorrhea (FHA).

FHA is the absence of menstruation related to suppression of the hypothalamic-pituitary-ovarian axis after other causes of amenorrhea have been excluded.

Low energy availability can be one contributor, but it isn't always about food alone.

High exercise demands, psychological stress, insufficient caloric intake, inadequate recovery, or a combination of these factors can contribute.

This is also why telling a woman with an irregular or missing period to simply “eat more” may not address the entire picture.

I want to know:

Is she eating enough overall?

Is she meeting her protein, carbohydrate, and fat needs?

How much is she exercising?

Has her exercise recently increased?

How is she sleeping?

What is happening with her stress levels?

Has her weight changed?

Is she ovulating?

Are there thyroid, prolactin, PCOS, pregnancy, medication, or other medical considerations that need to be ruled out?

We have to look at the whole woman, not one symptom.

You Don't Have to Be Underweight to Be Under-Fueled

This is one of the biggest misconceptions I see.

You can have a “normal” BMI—or live in a larger body—and still have inadequate energy availability.

Energy availability isn't determined by appearance alone.

Someone who is exercising intensely, chronically restricting calories, skipping meals, or failing to adequately fuel her activity may experience physiological consequences regardless of what she weighs.

That is why assessment needs to be individualized.

Rather than looking only at body weight, I want to understand dietary intake, activity and exercise demands, menstrual history, sleep, stress, recovery, weight changes, GI function, and the person's overall health picture.

So, What Should Women Be Eating?

There isn't one perfect hormone diet for everyone.

There are, however, some important foundations.

Protein matters. The basic adult protein RDA is 0.8 g/kg/day, but that represents a minimum recommendation for most healthy adults rather than necessarily the optimal amount for every woman. Needs may be higher with aging, resistance training, increased activity, illness, recovery, or other individual circumstances.

Protein provides amino acids required for muscle tissue, enzymes, neurotransmitters, immune proteins, and countless other processes.

Dietary fat matters, too. Cholesterol is a precursor used in steroid hormone synthesis, and dietary fats also provide essential fatty acids and support cell membranes and absorption of fat-soluble vitamins. Extremely low-fat diets may therefore be inappropriate for some women.

And please don't be afraid of carbohydrates.

Quality carbohydrate sources such as fruit, vegetables, beans, lentils, oats, quinoa, potatoes, and other whole-food carbohydrates provide energy along with fiber, vitamins, minerals, and phytonutrients.

A colorful, plant-forward diet can also provide a wide variety of polyphenols and antioxidants that support cardiometabolic and overall health.

Then there is one nutrient I think we still don't talk about enough:

Fiber.

Fiber feeds portions of our gut microbiota, and fermentation of certain fibers produces short-chain fatty acids such as butyrate. These metabolites play important roles in intestinal health, including supporting the intestinal epithelial barrier.

Instead of asking, “What else can I remove from my diet?” sometimes the better question is:

“What does my body need more of?”

What About Exercise?

Exercise is one of the most powerful tools we have for supporting long-term health and longevity.

But exercise also creates a demand that needs to be fueled.

I like to think about it this way:

Exercise + Fuel + Recovery = Adaptation

When I work with clients, I want to know what kind of movement they actually enjoy, because the best exercise program is one they can realistically maintain.

Then we look at the bigger picture: strength training, walking, cardiovascular exercise, recovery, sleep, nutrition, and the amount of stress already present in their lives.

More exercise isn't automatically better.

I've worked with women who train hard, add more cardio when their weight plateaus, restrict their food further, and then become frustrated when they feel exhausted, bloated, poorly recovered, or notice changes in their menstrual cycle.

Sometimes the answer isn't another workout.

Sometimes we need to evaluate whether the body has enough fuel and recovery to support everything we're asking it to do.

When Your Cycle Changes, Pay Attention

If your periods disappear, become consistently irregular, or your cycle suddenly changes, don't simply assume it's something you have to live with.

And don't assume it's automatically perimenopause, either.

Menstrual changes can have many causes and deserve evaluation.

Once medical causes are considered, this is also an opportunity to evaluate the foundations:

Are you eating enough? Are you recovering from exercise? Are you sleeping? Are you under chronic stress? Are you meeting your nutritional needs?

For some women, continually eating less and exercising harder can move them further away from the health outcome they're trying to achieve.

Why This Is Personal for Me

This subject is especially important to me because I've lived through years of infertility myself.

I'm now pregnant at 46, but the road here was anything but straightforward.

Over the last 10–15 years, there were periods when I exercised intensely without adequately fueling my body. There were also periods of significant stress when I struggled with hormone changes and couldn't understand why my body wasn't responding the way I expected it to.

At one point, I assumed what I was experiencing was simply perimenopause.

Looking deeper at my own health and having my nutrition education taught me me how important it is not to reduce women's health to one hormone, one lab value, one diet, or one symptom.

And it reinforced something I now tell women all the time:

Foundations before fixes.

Nutrition cannot guarantee fertility. It may not be the only cause of infertility or even your perimenopause or menopause symptoms.

But nutrition, adequate energy availability, movement, recovery, sleep, metabolic health, and stress management are foundational pieces we can influence.

Whether you're struggling with fertility, navigating perimenopause or menopause, experiencing menstrual changes, or simply feeling like your body isn't responding the way it used to, sometimes the answer isn't to restrict more.

Sometimes it's time to look at the whole picture.

Wondering What's Actually Going On With Your Hormones?

If you're eating less, exercising more, and still feeling like your body isn't responding—or you're experiencing changes in your cycle, energy, sleep, digestion, or other hormone-related symptoms—there may be more to explore than calories alone.

I work with women to look at nutrition, lifestyle, metabolic health, digestive health, and hormone patterns together so we can identify the foundations that may need support.

Schedule a Complimentary 20-Minute Discovery Call

Because your body isn't a calorie equation. It's a connected system.

In Health,

Angie Hartman MS, NBC-HWC