Nutritional Metabolism


In lecture 10, we apply all the concepts that we’ve learned in the first 9 lecture to understanding how calories are burned in a human being.

We will cover the four areas of metabolic output:

Resting Metabolic Rate Thermic Effect of Food Non Exercise Activity Thermogenesis Exercise Activity Thermogenesis For each of these areas, we’ll discuss the variables at play which can cause your metabolism to be either faster or slower.

Key Takeaways

Within those topics we’ll cover some other critical concepts, such as:

  • How to use various formulas to identify metabolic rates, and how to determine how much calorie output an exercise causes
  • How endurance and strength training combat one another at a biochemical level.
  • Identifying ways for clients to make progress outside of the gym and nutrition

key outcomes

  • Identify factors that influence BMR, TEF, NEAT and EAT
  • Name the most important factor that determines RMR
  • Name two equations to calculate RMR
  • Explain how mTOR and AMPK interfere with one another

Key terms

  • BMR
  • TEF
  • NEAT
  • EAT
  • Mifflin-St. Jeor equation
  • Katch-McCardle equation
  • mTORC1
  • AMPK

Optimizing Metabolism through Nutrition & Lifestyle

What burns calories?

TDEE Total daily energy expendeture

RMR - resting metabolic rate

the base rate that you burn not doing anything. Age, sex, growth stage, lean body mass, hormones are factors Genetics, stress, pregnancy, temperature are more factors

Resting (or Basal) Metabolic Rate

  • literally if you didn’t move

  • 65% of your entire metabolism is encompassed here Where does it go?

    • 6 cal/lb for skeletal muscle
    • 2 cal/lb for fat
    • ~90 cal/lb of liver tissue
    • 100 cal/lb for brain tissue
    • 200 cal/lb for heart tissue

You pretty much want to change your skeletal muscle

Single most critical component of RMR is Fat Free Mass

Mifflin-St. Jeor equation

BMR = 10* Weight (KG) + 6.25 Height (CM) - 5 * AGE (Y) + S(KCAL/DAY)
S = +5 FOR males and -161 for females

Katch-McArdle equation

input an exact body fat %

BMR = 370 + (21.6 * FFM in KG)

Strength and Aerobic Training Results in RMR increase

“We conclude that aerobically trained and resistance-trained males have higher resting energy requirements independent of FFW compared with untrained males”

TEF Thermal Effect of Food

Macro composition Processing

The more processed your food is the less energy it takes to consume

people assume 10% for TEF when eating a western diet (low)

Obese individuals have significantly lower TEF in response to 400cal meal than lean individuals whether it’s a cause or effect is uncertain

10% TEF for ‘normal’ lifestyle and 25% TEF with training and eating whole foods

NEAT - Non Exercise Activity Thermogenesis

Fidgeting, Day Job, Time standing, genetics

usually larger than the calories burned inside gym

huge variation in NEAT 15% to 50%

For an 8 hour period

  • Chair bound: ~280 cals
  • Seated with ability to stand and move: ~650 cals
  • Standing: ~860 cals
  • Strenuous work: ~2250 calories

simply walking at 1 mile per hour doubles your energy expenditure over pure rest

Neat - Genetics

  • According to a recent review, up to 57% of the variability of spontaneous activity is thought to be genetic
  • Spontaneous physical activity levels cluster in families and could prospectively help to explain the propensity for weight gain
  • Twin studies also indicate a strong genetic association for NEAT, but it is not absolute…
    • One twin ended up losing over 25 lbs, whereas the other lost just 7 lbs

Other factors

  • sex is only important as it relates to societal constructs around work
  • elderly subjects perform 29% less
  • Industrialization We’re moving less throughout the day because technology is making us move less
  • time spent in activity is twice as likely during the summer as compared to winter months

NEAT and Over-Eating

study with 16 people eating 1000+/d more calories than needed for 8 weeks.. some didn’t gain much weight while others gained 10lbs

some people subconsciously move more — fidget

15-27% increase in NEAT when calorically restricted when exercising but if you exercise too much or too intensely can decrease your NEAT

EAT exercise activity thermogenesis

intensity, duration, modality, body mass

not all movement is equal Two factors

  1. The energy you burn performing the exercise
  2. the adaptations that occur as a result of you performing that movement

Various exercises

  • Fast walking is about .1 calorie per kg of body weight per minute (4mph)
  • running a little faster (5mph), 30% increase
  • running twice as fast (10mph) , 2x calories burned — .28 cals per kg per minute
  • Cycling at 13 mph burns about .1 cal per kg of body weight per minute.
  • Biking twice as fast increases the output to .3 cal/kg/min

spend more energy than a smaller person.

Training Adaptations to Exercise

Resistance training

  • mTORC1 - protein synthesis hypertrophy

Endurance training

  • AMPK - mitochondria biosynthesis
  • generates TSC 1/2 proteins that block mTORC1

need to time it right.

Eat a High Protein, high Fiber minimally processed diet, and ‘take the stairs’

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