What Under-Eating Does To Your Body

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What Under-Eating Does To Your Body

You may not think you’re under-eating because you’re not losing weight. But understand that just because you’re eating 1200 calories and maintaining your weight, doesn’t mean you’re thriving and you VERY WELL could eat WAY more food and maintain your weight in a much healthier place.  

How do we know about how many calories we burn in a day?  There’s really no way to know exactly BUT...we can estimate: 

  • BMR - body’s basic needs (1200-1600 calories/day minimum for females on average) 
  • NEAT (400-500 calories for 10k steps/day) 
  • Exercise (varies a TON! But for 45-60 minutes of a workout, likely around 250-350 calories) - running/cardio burns higher PER session, but in long-run, weight training burns higher levels due to muscle mass maintenance needed 
  • Thermic Effect of Food - For 2000 calories consumed, about 100-200 calories are burned (source).
  • That totals up to around 2000+ calories for most women.

You can also utilize the TDEE calculator to check your personal TDEE HERE.

What do we consider under-eating

  • Bigger than 500 calorie deficit compared to total daily energy expenditure (1400 or less calories) 
  • CONSISTENTLY doing this most of the week - if you think you are doing this, but you are gaining weight - you likely aren’t eating this small of amount of food with large fluctuations. 
  • Not matching intake to additional/excessive exercise
  • Eating in a large deficit for more than 3 months in a row 

What Happens to the body when we are in this state of under-consumption compared to our output? 

  • Thyroid Gland Hormones - Your thyroid is host to a number of different hormones, one being triiodothyronine (T3), which is known to play an important role in regulating metabolic rate.  When your thyroid is properly supported with enough calories and carbohydrates, it will show increases in circulating thyroid hormones, which often means an increase in metabolic rate. Whereas lower levels of intake or restriction have shown lowered thyroid levels which result in decreased overall metabolic rate [1]

Hormonal Impacts -

  • Leptin - This is your ‘satiety’ hormone, which regulates fat storage and how many calories you eat/burn.  Caloric restriction and lower body-fat levels are shown to decrease the amount of leptin produced (meaning we don’t get as full as easily!) [2]
  • Testosterone - This hormone is primarily known for its role in increasing and maintaining muscle mass, which helps to increase resting metabolic rate.  Testosterone has also shown links in fat-tissue regulation. Research suggests that high testosterone may subdue adipogenesis (your body’s ability to form fat-cells).  In a calorie deficit, testosterone decreases, which then in turn may correlate with higher fat storage [3]. Low testosterone can also impact your libido and we often see a drop in sex drive with sustained calorie restriction.  
  • Cortisol - Cortisol is our stress hormone, and a calorie deficit is an additional stress on the body because we are not supplying the body with adequate energy to function optimally.  When energy is restricted (i.e. calorie deficit), research shows that cortisol will rise. [4]  This rise in cortisol has shown to impact macronutrient metabolism and actually start to break down muscle mass instead of fat. [5]
    • Metabolic Response - 
      • BMR - BMR is your basal metabolic rate, or how many calories your body burns in a day at rest (to keep your brain functioning, heart pumping blood, etc.). When you lose weight, you are losing either fat tissue, muscle tissue, or both.  These are both forms of metabolically active tissue, meaning they burn calories at rest. So as we lose weight, we are losing total calories burned in a day as well. [6] 
      • NEAT - Non-exercise activity thermogenesis refers to how much we move in a day aside from exercise.  Our fidgeting, how many steps we walk in a day, chewing food, standing, etc. It has been shown that when you are in a calorie deficit, NEAT naturally decreases subconsciously as a way for your body to conserve energy [7]. 
      • TEF - The thermic effect of food refers to the amount of energy it takes the body to break down, digest, and absorb nutrients from our food. It is estimated that about 10% of our total daily energy expenditure, or how many calories we burn in a day, comes from the thermic effects of food [8].  So as we eat less calories in an attempt to lose weight, we also see a decrease in the thermic effect total burn of calories as there is less food to breakdown.   
  • Bio-Feedback Response 
    • Bowel movements have slowed down in frequency and/or constipation is happening often.
    • Sleep quality has decreased. 
    • Hunger levels are increasing. Cravings increase.
    • Performance in the gym has severely declined and/or injuries are starting to occur more frequently.  These are both signs your body is under-recovering. 
    • Mood swings are becoming more frequent. 
    • The scale is no longer moving and you may actually be seeing weight gain, even with adherence. 
    • You’re noticing more extreme fatigue/tiredness and lacking energy throughout your day.  
    • Sex drive has decreased.
    • Females: Periods have become irregular or stopped altogether. 
    • You’re getting sick more often. 

This is why we created Metabolic Prehab, to help women get out of the place of restriction and bring your body back to health.

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