Buzz word galore. I kept hearing (and even reading) about hormones like leptin and insulin, but I never really understood them. As I was sick last week, I finally took the time to read up on them. My notes are as follows (if anything is wrong, let me know).

Leptin

• Leptin equates to a level of “available energy” for your body
• Secreted by your fat cells
• In rats, obese rats had no leptin. Inject with leptin, fat loss incurred quickly
• Rage over leptin as the miracle weightloss
• Contrary to rats, overweight human beings had high leptin levels
  • Overweight people had developed resistance to leptin (similar to insulin resistance)
  • Essentially the signal from leptin to brain was broken somewhere
• Injecting overweight humans with leptin provided no real weight loss
• Leptin scales with subcutaneous fat (higher in woman) [Inversely, insulin scales with visceral fat, higher in men]
• Estrogen seems to increase response of leptin
• Leptin levels do not change quickly (can take hours)
• Males below 10% bodyfat have almost no leptin in their bloodstream
  • Women have 2-3x leptin compared to men with equal BF%
• Leptin seems to respond directly with carbohydrate metabolism in fat cells
  • Responds to both over and under-feeding
• After a week of dieting, leptin drops 30-50%
• Short-term carb overfeeding can bring leptin levels up (faster than fat is gained)
  • Only responds to carb-intake. Overfeeding on fat does not produce a similar response
  • Refeeds are used for both leptin and insulin
• Leptin basically tells your body:
  1. How much fat you are carrying
  2. How much you are eating
• Leptin is involved in a lot of stuff, including:
  • Fat oxidation
  • Liver metabolism
  • Immune system
  • Hunger regulation
  • Libido
    • Too much body fat also impacts libido negatively due to insulin resistance
  • Possibly more
• Levels are critical for puberty and fertility
  • Need a minimum level of fat for puberty. Childhood obesity -> higher leptin levels -> earlier puberty
  • Without enough leptin (“energy”), body decides reproduction not as important, shuts down reproductive system
  • Raising leptin brings back reproductive function without weight gain
• Leptin is basically a safeguard from starving. With not enough “energy” body slows itself down
• Lower levels of leptin could also impact dopamine signalling (aka increased resistance)
• Existing fat levels matter. Losing 5% of BF at 30% BF does not trigger the same response as losing 5% of BF at 10% BF
• Low leptin levels also make it hard to feel satiated
  • Conversely, in the short term, leptin tells your body it is full
• As a supplement, leptin has to be injected. Pretty much impossible to get and *very* expensive
• Best way to raise leptin is a high carb/high calorie refeed of at least two meals (eg lunch + snack).
  • Need multiple meals as leptin does not change quickly like insulin
  • The leaner you are, the more refeeds are important in restoring leptin levels
• Zinc and Vitamin E *may* have an impact on leptin production
• Exercise and fish oil also *may* improve leptin transport (aka sensitivity)
• Blood triglycerides seem to be cause of resistance (lower in high fat diets)
• Insulin (not excessive amounts) and epinephrine increase leptin transport
  • Insulin stimulates leptin release
• Inflammation (omega 6/3 ratio) also increases leptin resistance
• Refeeds should be high carb, moderate protein, low fat
  • Post workout is optimal time
  • Eg, Mark Sisson recommends 250-300g. Martin Berkhan targets 100-150g.
• Short term cortisol increase can help leptin levels
• Intermittant fasting (IF) is possibly positive – during fasting it falls, but breaking fast/refeed elevates it
  • In one study, mean leptin levels are increased. In a Ramadan study, the mean was the same
• High amounts of fructose increases leptin resistance

Cortisol

• Aka the stress hormone
• Good in short-term, bad long-term
• Used in:
  • Blood pressure
  • Regulates immune system
  • Metabolism
• Normally peak in the morning, dips in the evening
  • Slugishness in the morning is due to low cortisol levels
  • Lack of adquate sleep decreased peak and increased dip
• Short term elevation can:
  • Elevate mood
  • Increase leptin levels
  • Improve insulin resistance
• Chronically elevated provides the opposite of short-term:
  • Depression
  • Reduces leptin levels
  • Water retention (diuretic)
  • Decreased testosterone
  • Indirectly promotes storage of fat
  • Muscle breakdown
  • Conversion of protein to glucose in liver
  • … and more
• Ways to control (decreased ‘body stress’):
  • Adequate sleep
  • Exercise
  • Fasting can bring it down
  • Don’t go into too much caloric deficit
  • Do not overtrain (eg excessive cardio)
  • Antioxidants and healthy fats could also help regulate
  • Omega 3/6 balance (keep body away from inflammation)
  • Research by Bulgarians showed that workouts > 45 minutes increased cortisol
  • Bulgarians did multiple 45 minutes sessions in a day
  • Over-feeds can also decrease (by decreasing stress on body)
• NOTE: Your body DOES need it. Just not elevated periods all the time. Only in short term peaks

Insulin

• Used in regulation of carb/fat metabolism
  • Used to stimulate glycogen storage in liver
    • Thus lowers blood glucose level
  • Decreases protein breakdown
    • Drives amino acids into muscle
  • Directly inhibits fat mobilization from fat cells
    • Even in a fasted state insulin blocks lipolysis
• Fear of insulin is a bit excessive
  • Needed to keep leptin levels high
• Is raise by consumption of carbohydrates OR protein
  • Protein does not cause increase as much as carbs
    • Proten does release glucagon (carbs do not)
      • Glucagon increases blood glucose level
      • Glucagon is kind of ying/yang to insulin
  • Raises more when both consumed
  • Basically spikes when food is being absorbed and dips when none left to absorb
• Genetics can greatly affect insulin sensitivity (upto 10x)
  • Thus while a low-carb diet may work for Person X, for Person Y a high-carb diet would be more apt
• Working out with higher sensitivity leads to more GLUT4 activation and thus better workouts
• Increase sensitivity with:
  • Exercise (glycogen depletion)
  • Fish Oil (EPA)
  • Fasting (glycogen depletion)
  • Thus more sensitive at breakfast
  • Cinnamon
  • Moderate alcohol
    • Even for people with type 2 diabetes
• Insulin scales with visceral fat (higher in men) [Inversely, leptin scales with subcutaneous fat, higher in women]
• Levels can change in minutes
• High resistance issues:
  • Harder to build muscle
  • Libido decreases
  • Increase in blood sugar
  • Promotes fat storage
  • Fatigue
  • Increase in triglycerides
  • Increased hunger (unable to satiate properly)
  • Can cause diabetes
    • Diabetes is due to either not enough insulin (type 1) or body does not respond to insulin produced (aka resistance)
    • Over 40% of Americanos have some form of pre-diabetes suggestive of insulin resistance
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  • Plaque build up in arteries
    • Causes heart disease
  • Thyroid problems (due to inablity of liver to convert thyroid hormone T4 into T3)
• High resistance can be caused by:
  • Overeating
  • Excessive fructose/sugar (high blood sugar)
  • Glucosamine (taken for joint health) *may* also cause insulin resistance
  • Overweight (high BF%)
    • High levels of insulin do not directly cause obesity

Testosterone

• Useful for:
  • Libido for both men and women
  • Muscular growth
  • Bone densification
  • Hair growth
  • Estrogen production (via estradiol)
• Men have 10x compared to women
  • Women are far more sensitive
• Mostly made in testes / ovaries
• Decreased by:
  • Increased cortisol
  • Excessive cardio
  • Alcohol binging (10+ beers)
  • Low leptin levels (dieting)
• Increased by:
  • Fasting
  • Exercise
    • Lifting heavy things
      • Pause at least 90s between exercises. Shorter pauses promote growth hormone more
    • Sprinting
  • Sufficient Vitamin D
  • Sufficient Zinc
  • Clean meat
    • Bull meat has roughly 35x testosterone levels compared to steer meat
  • Saturated and monounsaturated fats
  • Cholesterol
  • Limited blood sugar spikes (less than 75g of glucose)
  • Refeeds/overfeeds
• Not affected by short-term fasting (eg leangains)
• Moderate doses of soy do not impact testosterone levels

Triglycerides

• Roughly 90% of the fat we consume (cholesterol is the other 10%)
  • The main component of vegetable oil and animal fat
  • Energy source and transporter of dietary fat
• Molecularly looks *nothing* like cholesterol
• Trans fat, monounsaturated fat, saturated fat, and polyunsaturated fat are all triglycerides
  • Trans fat – comes in refined foods
  • Monounsaturated fats: found in most food that have dietary fat (eg eggs and beef).
  • Saturated fat: found mostly in animal products
  • Polyunsaturated: liquid at room temperature, generally have a higher omega 6 to 3 ratio
• Trans fat is not really good for you
  • The other three have both benefits and drawbacks
• Stored and released by fat cells
• High levels correlates with insulin resistance
• Increased by:
  • Refined carbohydrates
    • Excess fructose (> 50g)
  • Obesity (fat storage)
• Decrease by:
  • Moderate alcohol
  • Higher fat in diet
  • Increase insulin sensitivity
  • Exercise
  • Fish oil / omega 3
  • Vinegar
• Excessive amounts leads to:
  • Atherosclerosis / heart disease / stroke
  • Lowered leptin transport

Sources include Examine.com, Lyle McDonald, Martin Berkhan, Mark Sisson, Stephan Guyenet, Ryan Koch, Don Matesz, Chris Masterjohn, Wikipedia, and more.

Broscience was ignored, citation was required.