Category Archives: diet

Does junk food make you lazy?

Posted on April 9, 2014 | 26 comments

From Times LIVE: “Does junk food make you lazy?” 

“A diet rich in processed foods and fat – and the extra weight that comes along with it – may actually cause fatigue, a lack of motivation and decreased performance, according to a recent study involving lab rats… excessive consumption of processed and fat-rich foods affects our motivation as well as our overall health.”

(this is categorically false as both diets used in the study being discussed were very low in fat.)

And from Psych Central: “Rat study shows junk food can make you lazy”

The theory itself isn’t too far-fetched: a crap diet can cause weight gain and reduced energy expenditure, or a tendency to minimize any kind of physical activity… instead of: “’laziness’ causes obesity.”  And whether or not it’s true, unlike what some would have you believe, this wasn’t the study to prove it.

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Posted in Advanced nutrition, diet, Dopamine, empty calories, Energy balance, Sugar

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Meat digestion – fresh and raw or medium rare.

Posted on April 3, 2014 | 25 comments

“If a dog team is worked hard daily for two weeks and fed with fresh fish caught under the ice and frozen without opportunity of becoming high, that team will lose weight and show definite signs of wear and tear.  If the team is fed with hung or high fish, they will be as good at the end of that time as the start, and often will have put on a little weight.”

-quote from a cool book Duck Dodgers sent me about digestive enzymes. 

“High” doesn’t mean psychedelic, but rather letting the meat sit for a time so as to allow it to tenderize, or “pre-digest.”

One study showed that protein breakdown, measured by desmin degradation, increased by roughly 33% if the meat was removed from the cow 24 hours after slaughter (“conventional”) instead of immediately after (“rapid”) (King et al., 2003).

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Posted in Advanced nutrition, diet, fermentation, microbiota, Protein

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Carbohydrates, calories, appetite, and body weight.

Posted on February 2, 2014 | 36 comments

The Optimal Diet, Atkins, South Beach, Paleo, Zone… all have one thing in common: some degree of carbohydrate restriction.

Low, lower, lowest: does it matter?

There are 4 relatively large, randomized ‘diet-induced weight loss’ studies that all reported fairly comprehensive food intake and body composition data. The studies ranged in duration from 24 weeks to one year and included anywhere between 50 and ~300 overweight and obese participants.

In general, participants assigned to the low fat intervention were advised to restrict calories and fat whereas those assigned to low carb were told they could eat as much as they wanted as long as it wasn’t carbs.

Your mileage may vary – but these studies cover a large number of subjects from a wide range of backgrounds, suggesting the results might be applicable across the board.  Conclusion?  the amount of body fat lost was much more strongly associated with the reduction in carbohydrates than calories.  The only modestly surprising aspect was the magnitude… (see the figures below).

The four studies, in chronological order:

Brehm 2003: over the course of 6 months, those who consumed an average of 163 grams of carbohydrate per day lost 8.6 pounds of body weight while those who consumed 97 grams lost 18.7 pounds.

McAuley 2005: 24 weeks; those who ate 171 grams lost 10.3 pounds, while those who ate 133 grams lost 15.2 pounds, and those who ate 107 grams lost 15.6 pounds.

Maki 2007: 36 weeks; those who ate 186 grams lost 5.7 pounds, those who ate 131 grams lost 9.9 pounds.

Gardner 2007: 1 year – those who ate 138 grams lost 10.3 pounds, 181 grams lost 3.5 pounds, 195 grams lost 4.8 pounds, and 197 grams lost 5.7 pounds.

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Posted in Advanced nutrition, diet, Dietary fat, Energy balance, fat

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Ketoacidosis

Posted on January 8, 2014 | 93 comments

Nutritional ketosis is a normal, physiological response to carbohydrate and energy restriction.  A ketogenic diet is an effective weight loss strategy for many.  Ketoacidosis, on the other hand, is a pathological condition caused by insulin deficiency.  The common theme is low insulin; however, in ketoacidosis, blood glucose levels are very high.  Ketone levels are elevated in both states, although are 10-20x higher in ketoacidosis (~0.5-2 vs. > 20 mM).  Nutritional ketosis and ketoacidosis should not be confused with one another, and a ketogenic diet doesn’t cause ketoacidosis.

In ketoacidosis, gluconeogenesis occurs at a very high rate and the lack of insulin prevents glucose disposal in peripheral tissues.  Skeletal muscle protein breakdown contributes gluconeogenic substrates, exacerbating the problem.  This can cause blood glucose to reach pathological levels, exceeding 250 mg/dL.

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Posted in Advanced nutrition, diet, Dietary fat, fat, insulin

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Gut microbiome & short-chain fatty acids: resistant starch vs. prebiotics

Posted on December 30, 2013 | 105 comments

Bifidobacteria undoubtedly like resistant starch (RS).  They bind and hold on tight, an effect mediated by cell surface proteins.  Big thanks to Tim Steele for passing along many of the studies cited here.  One of said studies showed that treatment of bifidobacteria with proteases abolished the RS binding; but even dead critters would bind if their cell surface proteins were intact (Crittenden et al., 2007).  

I suspect fermented foods have this all figured out.  The microbes in sauerkraut are going to be embedded in & all around the cabbage polysaccharides; likely protected from digestive enzymes (to a degree) and holding on tight.

Something similar has been shown for galactooligosaccharides (GOS) (Shoaf et al., 2006).  In this study, GOS, but not a variety of other fibres, inhibited the binding of pathogenic gut microbes to intestinal epithelial cells.

These mechanisms are likely not mutually exclusive, and both seem like they could benefit the host (us).

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Posted in Advanced nutrition, chocolate, diet, Grains, microbiota

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On resistant starch and blood glucose control

Posted on December 20, 2013 | 100 comments

For overall health and well-being, fermented foods like sauerkraut and kefir are great.  Especially when following a low carbohydrate diet which is generally low in the types of foods which feed the gut microbiome.

For those with gastrointestinal problems, the gut microbiota is probably involved.  Whether it is bacterial overgrowth or dysbiosis, gut bugs are usually the culprit.  Treatment options vary widely, ranging from global extermination with vinegar & a low fibre diet (as per Jane Plain), or remodeling the microbiome with a prebiotic like galactooligosaccharides.   Probiotics like bifidobacteria can help, too, if they’re administered with either prebiotics or fermented foods (they need something to nourish them in transit).  Dark chocolate is also an excellent vessel.  Resistant starch is another option, although the question remains as to whether or not this is compatible with a low carbohydrate diet.

Resistant starch has been around for a while, and when I was in school it received about 10 minutes of attention during the fibre lecture.  But Jimmy Moore and Richard Nikolay have been talking about it a lot lately so I decided to freshen up on the topic.  In brief, it can be therapeutic for GI issues, but some studies have shown mixed effects on glucose & insulin metabolism.  The former is virtually unarguable, but I found the latter interesting.  And the impact of resistant starch on ketosis is included as well.

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Posted in Advanced nutrition, clamp, diet, fiber, Grains, insulin, Ketosis

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Dietary protein, ketosis, and appetite control.

Posted on December 6, 2013 | 118 comments

“Dietary protein has a purpose, and that purpose is not carbs.”  Nor is it to break ketosis or stall weight loss.  

Drastically increasing protein intake may reduce the degree of ketosis in the context of a large energy surplus, but this is likely due more specifically to the large energy surplus than the protein.  This would explain why Warrior dieters (1 meal meal per day) often report reduced ketones if they eat too much protein.  It’s more likely that the 2000 kcal bolus is exerting it’s anti-ketotic effect by being a large energy surplus, such that anything other than 90% fat would blunt ketosis.  It’s not the proteins… Want proof?  Here’s an n=1 to try: give up Warrior dieting for a few days and try 3 squares.  My bet is that you’ll be able to increase protein intake and still register ketones as high or higher than before.  There are data to support this and reasons why it may not matter (below).

disclaimer: I don’t think “deep ketosis” is necessary to reap the benefits of carbohydrate-restriction.  But if you love high ketone meter readings, then this might be a better strategy to maintain deep ketosis while getting adequate protein. win-win.

if I hear: “oh no, I was kicked out of ketosis!” one more time… 

All of the studies below are confounded one way or another, but so are we humans.

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Posted in Advanced nutrition, diet, Dietary fat, Energy balance, fat, insulin, Ketosis, Protein

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Dietary protein does not negatively impact blood glucose control.

Posted on November 29, 2013 | 85 comments

“Dietary protein-derived amino acids have a purpose, and that purpose is not carbs.”

At a reasonable level of dietary intake, protein is used for the maintenance of organs & tissues.  Lean body mass.  It’s functional.  Protein isn’t stored in any appreciable capacity, and most excess is either oxidized or stored as glycogen.  Theoretically, about 50-60% of protein-derived amino acids can be converted into glucose, mathematically, but it’s not what you think…

“At a reasonable level of dietary intake.”  A recent publication took a look at this (Fromentin et al., 2013).   They set out to determine how much protein is converted to glucose under “optimal gluconeogenic conditions.”  That is, the subjects were 12 hours fasted, which is a physiologically relevant, optimal gluconeogenic condition.  They were then given 4 eggs (~23 g protein) that were labeled with two stable isotopes (15N & 13C, derived from hens fed isotope-enriched diets!).  Throughout the entire study duration, the subjects were infused with a third isotope, 2H-glucose.  By collecting and analyzing the enrichment of isotopically-labeled metabolites like expired CO2, urea, and glucose, the researchers were able to determine the fate of those 23 grams of protein.

Some of the dietary protein-derived amino acids were used for protein synthesis, others were oxidized.  But blood glucose levels did not change.  Nor did the rate of gluconeogenesis.

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Posted in Advanced nutrition, diet, insulin, liver, Protein

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Implications of the circadian nature of ketones.

Posted on November 24, 2013 | 38 comments

Ketosis.  Happens during starvation and also by restricting carbohydrates (and protein, to a lesser degree)… might be important for epilepsy and bipolar disorder, too.

ketogenesis

Ketostix measure urinary acetoacetate (AcAc) and reflect the degree of ketosis in the blood probably about 2-4 hours ago.  Blood ketone meters measure beta-hydroxybutyrate (bHB) right now.  bHB fluctuates to a greater degree, eg, it plummets after a meal whereas AcAc takes longer to decline.  AcAc/bHB is usually around 1, but increases after a meal (Mori et al., 1990):Ketone body ratio

Conversely, when glucose levels decline and fatty acid oxidation increases, liver redox potential drops which reduces AcAc/bHB.

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Posted in Advanced nutrition, circadian, depression, diet, Dietary fat, epilepsy, Exercise, fat, Ketosis

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Low carbohydrate diets favorably impact testosterone levels.

Posted on November 17, 2013 | 43 comments

It is known.  Carbohydrate restriction improves (lowers) testosterone in women with PCOS.  It works for men, too… but by “works” I mean “increases.”

Decrease of serum total and free testosterone during a low-fat high fibre diet (Hamalainen et al., 1982) 

Intervention pseudo-crossover study: 30 healthy Finnish men in their 40’s were studied on their habitual high fat diet (40%  fat), then put on a low-fat (25%) high fibre diet for 6 weeks, then switched back to high fat.  The high fat diet was also higher in saturates, P:S ratio 0.15 vs. 1.25.

free T

 

Free testosterone levels declined on the low fat diet, but they recovered after 6 weeks of going back to their high [saturated] fat dieting (p < 0.01).

Some observational data: Testosterone and cortisol in relationship to dietary nutrients and resistance exercise (Volek et al., 1997)

…fat, and in particular saturated fat, is associated with increased testosterone levels [in men]:

observational

 

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43 Comments

Posted in Advanced nutrition, clamp, diet, Dietary fat, fertility, insulin, sex, testosterone

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