Chronic Undereating: Are You Eating Enough?

Written By


Expert Reviewed By

Dr. Lauryn Lax, OTD, MS

Dr. Lauryn, OTD, MS is a doctor of occupational therapy, clinical nutritionists and functional medicine expert with 25 years of clinical and personal experience in healing from complex chronic health issues and helping others do the same.

Smallmeal 1 | Chronic Undereating: Are You Eating Enough?

Will my metabolism ever be the same?: Fixing your metabolism from undereating

Chances are, if you’re a woman (91%), you’ve tried a diet at some point in your life as a means to control your weight or improve your body.

And dieting isn’t just a woman thing—1 in 2 people are on a diet at any given time—ranging from fads (intermittent fasting, the Pizza Diet) and weight loss efforts (Weight Watchers) to lifestyle changes (diabetes), athletic performance and health interventions (such as GAPS protocol for Autism).

What diets have you tried?

In my practice, I often see folks who are looking for a new and different way of approaching the whole dieting conundrum—no longer wanting to restrict or deprive themselves, but equally terrified that, without dieting in their back pocket, all hell is going to break loose.

“I’m so scared that if I just eat, and don’t care anymore, I’m going to gain weight,” said five different women this week alone.


There’s no question that dieting—especially yo-yo dieting or long term disordered eating does funky things to your body—particularly your hormones and metabolism.

The REAL question many of my clients wonder:

Will my metabolism ever be the same?!

Here’s a look at what chronic dieting and undereating does to your metabolism, how to fix it (and how to find peace with your body and food in the process).

Chronic Undereating: A Real Problem

Most of our society is hyperfocused on overeating—thanks to the war on Diabesity (the new term for diabetes and obesity), the push back against fast food and the evolution of more and more diet forms of packaged products we all know and love (gluten-free Cheerios, reduced fat Jiffy peanut butter, sugar-free pudding)…but undereating?! For real.


As in: Not eating enough to support your body’s needs.

And no, I am not just talking about dieting here—restricting food or manipulating your food for a particular outcome. I am also talking about straight up: Missing the mark on eating enough food in a given day due to things like:

  • Lack of appetite
  • Forgetfulness
  • Busyness
  • Worry and stress
  • Anxiety
  • Apathy
  • Budgeting
  • Lack of preparation

There are many reasons “chronic undereating” can happen.

Regardless of the root cause, here are some common indicators that you may be chronically undereating:

  • Stubborn weight gain
  • Difficulty losing inches, gaining muscle or shifting body composition
  • Loss of appetite or feelings of hunger
  • Fatigue or low energy
  • Decreased digestion
  • Constipation, bloating, gas or abdominal cramping when you do eat
  • Quickly full after eating
  • Brain fog
  • Feeling easily run down
  • Thinking about food often
  • Hormonal imbalances (loss of period, crazy PMS)
  • Plateaus in the gym
  • Adrenal insufficiency
  • Headaches
  • Dips and crashes during the day
  • Need for naps
  • Lowered immune function
  • Allergy sensitivities
  • Lowered libido

The tricky thing about undereating is that, often times, it messes with your hunger-fullness cues, so you easily get out of touch with even feeling hungry enough to eat in the first place.

Metabolic Mayhem

A big reason your intuitive eating skills are lost (your ability to know when you are hungry and full) is due to the toll chronic undereating takes on your metabolism.

When we are not giving our bod with the nutrients and balance it needs on a daily basis, our body goes, “Ok, well I guess I’m gonna have to deal with whatever it is you DO give me,” and it learns to adjust on the sub-par fuel sources you provide.

Before your undereating habits began, it may have begged you for breakfast, lunch and dinner, and maybe even a snack or two throughout the day…but as the habits of chronic undereating ensue, your body throws its hands in the air and says things like:

Alright—guess I’m going to have to make that Cliff Bar you ate for breakfast at 8 a.m. last until about 3 or 4 p.m. when you decide you want a frozen dinner meal, then a sushi roll tonight at dinner with your friends.”

Or, “That smoothie after your workout is all I’m gonna get until you decide to break out your chicken, broccoli and olive oil for lunch, and then your salmon and asparagus for dinner…so I suppose I will have to deal and it will have to do (even though, ahem, I really could use more fuel, thankyou very much).”

In other words: Your body WANTS to work for youit wants plenty of fuel so it doesn’t have to “just deal.”

Unfortunately, since you’re out of touch with what your body is asking for or giving it what it needs…YOUR METABOLISM SLOWS DOWN.

(Refresher: Metabolism = ALL of the chemical reactions inside our bodies needed to conduct life, balance and energy inside your body).

When your metabolism slows down, your body goes into “starvation and survival mode”, in which the body responds to your reduced food intake by reducing calorie expenditure and your physical energ in an attempt to maintain energy balance and prevent starvation.

Cortisol Conundrum

In the process of your metabolism slowing down from low food supply, your cortisol levels ramp up.

Cortisol is that special hormone that helps us react and deal with stress.

We need some cortisol to deal with scary or stressful situations in the short term (such as spiking and increasing our adrenaline to run away from a bear).

However, when cortisol stays around for longer than needed (such as when we are constantly undereating), it is responsible for throwing our hormones out of whack!

As cortisol goes up (from not eating enough), it steals the hormonal show:

  • Estrogen and testosterone sex hormones fall or rise (Enter: Low libido, mood shifts, apathy, weight and fitness plateaus… For example: Take a menopausal woman, but when you put her under a stressor—such as sugar cravings, poor diet or chronic undereating—her cortisol rises, she’ll get hot flashes—a symptom of estrogen deficiency.)
  • Leptin hormone levels decrease (Leptin is responsible for telling us when we are hungry or full; Lowered leptin also causes disruption in our reproductive levels and menstruation, leading to crazy PMS, irregular periods, infertility or amenorrhea)
  • Insulin levels become sensitive—sending us on a blood sugar roller coaster throughout the day (Insulin is responsible for balancing blood sugar in our body, but when it gets out of sorts, we experience poor blood sugar regulation—i.e. crashes, headaches, easily fatigued, and more. Cortisol prevents insulin from moving glucose—sugar and energy from our food—into our cells by decreasing the number of glucose transporters to the cell surface.).
  • Thyroid hormones take a hit—(Your thyroid hormones are responsible for controlling your metabolism and all of your body’s functions. If you have too little thyroid hormone in your blood, your body slows down—a.k.a.  hypothyroidism. When the body is pushed too hard, thyroid hormone and the metabolic rate goes down. High cortisol lowers thyroid hormones by preventing the conversion of your T4 inactive hormone to the T3 version of the hormone)

These hormonal imbalances can also trigger shifts in body composition, sleep cycles, energy levels and our basal metabolic rate.

For instance: sometimes, chronic undereaters don’t understand…

  • Why they gain weight easily or can’t lose weight
  • Why they are able to subsist off of “not much food” or, 
  • Why can’t seem to build lean muscle mass.

“I don’t get it! I am not even eating that much, but when I so much as look at a cookie, the pounds go on,” one says.

Another says, “I used to have a high metabolism and could eat practically anything…now, I’m not even eating that much, but I’m gaining weight.”

And still another says, “I’m just never that hungry. It’s not that I’m dieting—I just don’t feel hungry and I’m maintaining my weight.”

Resting energy expenditure is drastically reduced when we consume less than the ideal intake for our bodies. 

In a study comparing chronic undereaters to individuals with naturally lean body masses (who were NOT undereating), researchers found a significant different in the resting metabolic rate for the undereaters (i.e. they burned less energy at rest)—concluding this is an adaptive response, and the body turns to one’s own organs and muscle mass for “fuel” when it’s not getting enough through food.

Will I always be this way?

This being said, chronic undereaters I see in my practice often also fear…

  • Gaining weight
  • Restoring their metabolic function (is it all lost?!)
  • What will happen IF they begin to eat more

They ask, “Have I messed up my metabolism for good?”


“Can I fix my metabolism after a history of chronic undereating or dieting and eating disorders?”


Although it may seem like your lowered metabolism is a “lost cause”—fear not, your metabolism CAN be won.

(In fact, a study of chronic undereaters found that a dysfunctional metabolism can be restored when we eat proper energy for our body).

Restoring Your Metabolism.

Your former undereating habits and history took its toll on your body, but today marks a new day to reset.

Your body is SMART and it DOES want to restore balance to your hormones if you let it.

Where to start?

Here are 5 simple steps for healing your metabolism:

  1. Take Inventory. Chances are, you’re pretty out of touch with how food makes your body feel—or not feel. Before changing anything, first take inventory. For at least 3 days, keep your own mindful eating food log, and record:
  • The food you eat,
  • Your hunger and fullness levels before and after each meal (on a scale of 1-10, 1=famished, 10=stuffed)
  • And, how you feel and/or think before and after each meal (i.e. mood shifts, obsessive thoughts, energy dips, headaches, constipation, gas, etc.)
  1. Reflect. Review your food log. Look for any patterns or common side effects you notice in your physical wellbeing throughout the day (like “I get a headache most days around 3,” or “I crave sugar every night after a day of not eating much,” or “I’m always gassy and bloated after breakfast in the morning). These insights will help with moving forward as your begin to make positive changes.  
  1. Establish an Eating Schedule. Regular meals probably won’t feel normal or intuitive at first. You may have lost touch with your appetite throughout your undereating days, or adapted to infrequent or restricted eating patterns. Take a look at your daily schedule, and begin to pencil in regular meal times throughout the day. Snacks may or may not be part of your plan, but at least aiming for three balanced meals every 4-6 hours is a must.
  1. Define Balance. Protein, fat and carbohydrates are non-negotiables for human body optimization. Aim to get a protein source, healthy fat and colorful veggies—especially leafy greens—with every meal. And if you’ve been on the “low carb” or “low fat” or “no protein” train for awhile, reflect upon how it’s working for you. There is not a one-size-fits-all approach to the specific number or amount of each source you need, but general guidelines for a healthy thriving body include all three of these components. (See below to find out about getting your personalized plan)
  1. Check-in. You don’t have to go it alone. Seek the guidance of a nutritional therapist who can help you get on the right track. Book a free initial Spark session to connect with me at Thrive and find out how I can help you establish a customized nutrition plan, determine “how much” your body really needs and offer support along the way (100% individualized to you).
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