Metabolic Slowdown


In the 2nd half of the lecture we’re going to cover all of the changes that occur when we put ourselves into a calorie deficit. We will cover topics such as metabolic slowdown, adaptive thermogenesis, and discuss why the body adapts in this manner.

From there we’ll talk about ways to overcome these adaptations to ensure long-term sustainable progress for you and for your clients, with focuses on training, nutrition and lifestyle adjustments. FInally, we’ll cover scientifically backed approaches to cutting body fat, and how to adjust them for real world scenarios.

At the end of this lecture, you should be able to:

Key takeaways

  • Explain how the body adapts to a calorie deficit with regard to RMR, TEF, - NEAT and EAT
  • Define metabolic slowdown and adaptive thermogenesis
  • Explain what the purpose of these adaptations is
  • Discuss nutritional and lifestyle changes to reduce metabolic slowdown
  • Understand how the scale fluctuates in ways that are independent from fat loss
  • Use either the original or M2 modified versions of the MATADOR protocol, or the Bill Campbell protocol

Key Terms

  • Metabolic slowdown
  • Adaptive thermogenesis
  • Constrained versus additive models of energy expenditure
  • Metabolic “Damage”
  • “Starvation mode”
  • The MATADOR protocol

Your metabolism 100% does slow down when you lose weight

  • Can I prevent this?
  • Can I reverse it?
  • How MUCH does it slow down?
  • What can I do to minimize these effects?

What is Metabolic Slowdown

  • a catch-all term for anything that would decrease your metabolism

  • Multiple factors contribute to metabolic slowdown

    • Decreased Basal Metabolic Rate (BMR)
    • TEF decreases
    • EAT decreases
    • NEAT decreases
    • Adaptive thermogenesis occurs

Why does Metabolic Slowdown occur?

It’s completely normal. Information we need to adapt to not an actual problem

Can Metabolic Slowdown be reduced

Decreased Basal Metabolic Rate

  • less body means less BMR

20-25% of weight loss is fat free mass

Thermic Effect of Food (TEF)

less food being eaten means less being burned

less calories burned

Thermic Effect of Activity (TEA)

If you weigh less, you have less mass to move which means less calories burned

Is there a limit to your activity level?

Additive model vs constrained model

evidence against the constrained model

Adaptive thermogenesis

The decrease in the number of calories your body burns each day beyond what would be predicted to occur from changes in BMR, TEF, EAT and NEAT

your body sees your calorie deficit as potentially being in danger of starving to death

How big an effect? 15% up

How to reduce the impact of AT

  • Avoid too big of a calorie deficit (<20%)
  • minimize stress
  • avoid excessive high intensity exercise
  • avoid dropping carbs too low
    • massive impact on leptin, which is the hormone responsible for AT
  • use refeeds, diet breaks

reverse it? get out of a caloric deficit..

Summary so far… • Metabolic slowdown is real • It makes progress happen at a slower rate, requiring further adjustments to your calorie intake to maintain progress • Metabolic slowdown is NOT responsible for your inability to continue seeing progress/results • Adaptive Thermogenesis is real • It is a natural result of a calorie deficit • It cannot be avoided, but it can be reduced

Fake news

“Starvation Mode”

this isn’t a thing. If you’re in a deficit, you will lose weight

There is a response to starvation…

  • Absolutely…
  • Adaptive thermogenesis
  • Appetite increases
  • Awareness of food increase
  • NEAT decreases
  • Exhaustion increases
  • Leptin decreases
  • Ghrelin increases
  • Thyroid hormone decreases
  • Sex hormones decrease
  • Cortisol increases
  • Sleep quality decreases
  • Muscle loss increases
  • Strength, performance and recovery decreases

Metabolic damage real?

  • Metabolic Damage is the concept that long term, steep dieting is responsible for permanent damage to your metabolism
    • Theoretical causes include:
    • Losing too much weight
    • Losing weight too fast
    • Constant yo-yo dieting
    • Getting too lean
    • Anorexia Being on a very low calorie diet/crash dieting Doing too much cardio


from minnesota starvation experiment.. no signs of ‘metabolic damage’

How to generate long term results

Step 1: Strength train for hypertrophy

  • Increases your RMR slightly (slide 11)
  • Burns cals during exercise, and after (up to 38 hours)
  • Strength training seems to increase NEAT as well
  • Creating new muscle is an energetically demanding process Step 2: Optimize protein intake
  • Protein is the most thermic of the macros
    • ~20% TEF versus 0-15% for carbs and fat
  • Aim to eat 0.8-1.0 g/lb of body weight per day
  • Distribute into 4+ servings of 20-25+ grams
  • Use whole protein sources containing all 9 essential amino acids
    • Avoid BCAA and other isolated amino acids Step 3: Optimize Fiber Intake
  • Another very high TEF category of food
  • Slows down digestion
  • Beneficial for gut health as well
  • 25-40 grams/day
    • Depending upon size and total calorie requirement Step 4: Don’t drop calories too low.. growth hormone and testosterone plummet and cortisol skyrockets you burn more muscle mass than body fat Step 5: Sleep
  • 8 hours per night in a cool, pitch black room
  • Go to bed and wake up at similar hours each night
    • Important for generating a circadian rhythm
  • Lack of sleep impairs glucose tolerance and can reduce leptin levels
    • Two bad nights of sleep increases appetite by 25%
    • 4 poor night of sleep increases calorie intake by 20%
  • Should you manage to maintain your calorie deficit, you’ll just be losing muscle instead of fat Step 6: Stay Moving
  • avoid sitting for long periods each day
  • change work environment with standing desks
  • preplanned breaks for short walks

Why aren’t people losing weight?

“Known” Non Compliance

‘will power’ is waning due to mental stress of being in a calorie deficit for an extended period of time

this is NOT weakness, but instead evolution, making them think aobut food all day

What to do:

  • high quality
  • hyper-palatable foods practically drugs
  • increase consumption of the most satiating foods There are lists of most satiating foods white potatoes to name one
  • consider an extended break from the calorie deficit

“Uknown” non compliance

people believe they are eating a certain number but are actually eating more study showed 47%+ on average

Another study shows that people think they burn more than they really have.

we suck at estimation..

Not tracking progress appropriately

pros and cons Pros: see larger trends for weight loss Cons: doesn’t discriminate between fat and muscle.. can create stress and anxiety

Weight Counterbalance

  • Water retention
  • bowel issues
  • muscle mass gain

Preventing plateaus

They will occur at some point can be minimized by doing all the right things.

can be preplanned diet breaks can help this

MATADOR (minimizing adaptive thermogenesis and deactivating obesity rebound)

  • study on obese males

  • Breaks from your “diet” are not just good for your mental health, but clearly good for your physical and metabolic health as well.

  • Secondly, when you do take a “break” from your calorie deficit, it should be in a controlled fashion.

    • Ad libitum eating generally will drastically reduce the success of your diet overall

Real World Adjustments

  • A 33% calorie deficit is massive
    • This large of a deficit typically leads to binge eating issues
    • Also, we know that too large of a deficit leads to lost muscle mass
  • A 20% deficit is much more manageable
    • A nearly identical calorie deficit can be achieved over time by modifying the length of the diet break
    • A one week maintenance period also feels much shorter as well

refeeds show to maintain or even gain muscle mass while in an over-all caloric deficit over the months

Notes mentioning this note

Join the Newsletter