Russ's Grab-Bag Of Assorted PT Forum Goodness

[TheRuss]

Thanks for the kind words. I'm still a long way from getting my stupid ass properly educated, but in the meantime, hopefully I can at least point people to better sources.

[TheRuss]

It's been a while since I threw y'all a bone, so here goes.

To start things off, pop quiz: What's the main kind of fat in bacon? Saturated, monounsaturated, or polyunsaturated?

Spoiler:

Pork, cured, bacon, raw:

Saturated: 25.778g
Monounsaturated: 31.925g
Polyunsaturated: 8.184g

People throw around the word "high" a lot when it comes to fat, especially saturated fat. Trust the numbers, not the hype.

Spoiler:

And no, I don't know why "Total fat" is less than the sum of the three components.

Pop quiz, part 2: If you changed 1% of your caloric intake from carbs to bacon grease, what effect would you expect this to have on your HDL, LDL, triglycerides, and HDL:LDL ratio?

Spoiler:

Based on the numbers in this post:

HDL would go up by 0.0099 mmol/L
LDL would go up by 0.0083 mmol/L
Triglycerides would go down by 0.0239 mmol/L
HDL:LDL ratio would go up by 0.002

That's right. Bacon fat would potentially improve your lipid profile.

Spoiler:

Again, don't ask me why the individual numbers for change in HDL and change in LDL don't add up to change in total cholesterol.

Spoiler:

Also don't ask me how they managed to predict a HDL:LDL coefficient with constant HDL and LDL coefficients. If it were me, I'd have done the math more rigorously.

So when it comes to dietary fat, especially saturated fat:

Does it screw up your lipid profile? Probably not.
Does it raise your risk of cardiovascular disease? Probably not.
Does it raise your testosterone? Hell yes.

"But Russ, what about insulin sensitivity?"

I found a review article from 2008 that addressed this question (1). I like this review because it only includes high-quality trials that used reliable methods of determining insulin sensitivity*.

On to the meat of it. There were 5 studies in which non-diabetic people were fed diets rich in saturated fat, and compared with a group eating a diet rich in monounsaturated (like olive oil) or polyunsaturated (like corn oil) fat. They ranged in duration from one week to 3 months. Four of the five studies found that fat quality did not affect insulin sensitivity, including one of the 3-month studies.

The fifth study, which is the one that's nearly always cited in the diet-health literature, requires some discussion. This was the KANWU study (2). Over the course of three months, investigators fed 163 volunteers a diet rich in either saturated fat or monounsaturated fat.

-Whole Health Source: Saturated Fat And Insulin Sensitivity

From the KANWU study:

RESULTS: Insulin sensitivity was significantly impaired on the saturated fatty acid diet (-10%, p = 0.03) but did not change on the monounsaturated fatty acid diet (+2%, NS) (p = 0.05 for difference between diets). Insulin secretion was not affected. The addition of n-3 fatty acids influenced neither insulin sensitivity nor insulin secretion. The favourable effects of substituting a monounsaturated fatty acid diet for a saturated fatty acid diet on insulin sensitivity were only seen at a total fat intake below median (37E%). Here, insulin sensitivity was 12.5% lower and 8.8% higher on the saturated fatty acid diet and monounsaturated fatty acid diet respectively (p = 0.03)

-Vessby et al., "Substituting dietary saturated for monounsaturated fat impairs insulin sensitivity in healthy men and women: The KANWU Study."

Sounds pretty damning, right?

Actually, not so much.

The difference between the two treatments was of border line significance (p=0.05).

Actually, that's weasely. From the same Whole Health Source article:

After three months of these diets, there was no significant difference in insulin sensitivity between the saturated fat group and the monounsaturated fat group. Yes, you read that right. Even the study that's selectively cited as evidence that saturated fat causes insulin resistance found no significant difference between the diets. You might not get this by reading the misleading abstract. I'll be generous and acknowledge that the (small) difference was almost statistically significant (p = 0.053).

Bonus: It was strictly a comparison of saturated vs. unsaturated fat. I want a fat (saturated or otherwise) vs. carbohydrate insulin-resistance study - that's the really interesting question.

Double bonus: Remember what I was saying about "high"?

Notably, the detrimental effect of SFA versus MUFA on insulin sensitivity was primarily seen in subjects with a total fat intake below the median value of 37% of energy.

-Feskens, "Can diabetes be prevented by vegetable fat?"

If you're getting more calories from carbohydrate than protein or fat, that is a high-carbohydrate diet.

---

So what does impair insulin sensitivity? Fat, of course.

"Wait, what?"

Body fat, that is.

Obesity has been identified as the key aetiological condition that predisposes to the development of the metabolic syndrome....

Serum adipocytokine levels are elevated in obesity and interventions that reduce fat mass also lower adipocytokine levels. This relationship implies that approaches designed to reduce adipose tissue mass will attenuate the pro-inflammatory milieu that is associated with obesity-induced insulin resistance.

Roche, "Fatty acids and the metabolic syndrome."

And the testosterone! Won't somebody please think of the testosterone?

In males with increasing obesity there is increased aromatase activity, which irreversibly converts testosterone to estradiol resulting in decreased testosterone and elevated estrogen levels. Since androgens reduce the expression of ER beta activity, decreased testosterone levels release the normally suppressed ER beta expression and results in the down regulation of GLUT4 with resultant insulin resistance.

-Cohen, "Obesity in men: the hypogonadal-estrogen receptor relationship and its effect on glucose homeostasis."

Sure, it's just in "Medical Hypotheses", but I like the cut of his jib.

"So the key to higher testosterone and better insulin sensitivity is to be leaner. I should get lean by eating less fat, right?"

Wrong.

High-fat diets leading to excessive energy intakes are strongly linked to the increasing obesity in the United States. However, the prevalence of obesity has increased during the same time period that dietary fat intake (both in absolute terms and as a percentage of total dietary energy) has decreased.

-Lichtenstein, "Dietary fat consumption and health."

We've been cutting dietary fat but we keep getting fatter. This means that cutting dietary fat is not the answer.

Also, anecdotally, thus far, if there are significant quantities of carbohydrates in my diet at times other than post-workout, I chub up. If there aren't, I don't, regardless of how much I eat (and without carbs, I don't feel the desire to eat as much).

[Jack Rusher]

Also, anecdotally, thus far, if there are significant quantities of carbohydrates in my diet at times other than post-workout, I chub up. If there aren't, I don't, regardless of how much I eat (and without carbs, I don't feel the desire to eat as much).

Another anecdote: I eat an egg and bacon fry up over greens nearly every morning, foie gras four or five days a week, pork chops for dinner a couple nights a week, lamb and mutton a couple more, cheese and full fat yogurt every day, butter most days. We save the extra lard from our bacon and use it to cook everything else. Most nutritionists would recommend a life insurance policy, but I remain diesel with the blood work of a Bushman.

[Ming Loyalist]

Another anecdote: I eat an egg and bacon fry up over greens nearly every morning, foie gras four or five days a week, pork chops for dinner a couple nights a week, lamb and mutton a couple more, cheese and full fat yogurt every day, butter most days. We save the extra lard from our bacon and use it to cook everything else. Most nutritionists would recommend a life insurance policy, but I remain diesel with the blood work of a Bushman.

might have something to do with your workout ethic, dude. i think most nutritional guidelines are for people who don't understand what a workout actually is.

[PointyShinyBurn]

"But Russ, what about insulin sensitivity?"

I recently attended a talk by Susan Jebb of Cambridge about a study called RISCK where people were switched to one of four high/low fat and high/low carbohydrate diets (or a control group) on a proper randomised basis while remaining as close to iso-caloric as the researchers could make them.

Result was, in a nutshell, no impact on insulin sensitivity from differing macro-nutrient balance.

People did, however, disproportionately lose weight on the low fat arms of the trial even with the people running it begging them not to.

[TheRuss]

a study called RISCK

Target intake for total fat was 38%E in the HS and HM diets and 28%E in the LF diets, with carbohydrate intakes of 45 and 55%E respectively.

*sigh*

It is not a high-fat diet if you're getting more calories from carbs than fat. Oh well, let's see what they have for us...

Weight loss was significantly greater in both LF diets relative to the HM diets combined (P<0.0001) and HS/HGI diet (P<0.0001). However the absolute magnitude of the differences was small (≈1kg). There was no impact of GI on weight. Trends in waist and body fat were similar to weight, but there were no statistically significant differences between the diets.

(emphasis mine)
-Moore et al., "Impact of the Amount and Composition of Dietary Fat and
Carbohydrate on Body Weight, Waist and Fat Measures" (sounds like they presented this at a conference rather than publishing)

It's a shame. Sounds like they did put together a decent study, but they screwed it up with their selection of diets.

---

The reason I highlighted the change in fat is because when I did the high-protein diet (low fat, fairly low carb) thing, I wound up losing a lot of weight, but quite a bit of it was muscle.

[TheRuss]

might have something to do with your workout ethic, dude. i think most nutritional guidelines are for people who don't understand what a workout actually is.

Eh, exercise covers over a multitude of dietary sins, but my own experience covers eleven months of enforced inactivity, so that's not the only answer.

While I was looking for that RISCK study, I found this:

In short-term trials, a modest reduction in body weight is typically seen in individuals randomly assigned to diets with a lower percentage of energy from fat. However, compensatory mechanisms appear to operate because in trials lasting > or = 1 y, fat consumption within the range of 18-40% of energy appears to have little if any effect on body fatness. Moreover, within the United States, a substantial decline in the percentage of energy from fat consumed during the past two decades has corresponded with a massive increase in obesity. Diets high in fat do not appear to be the primary cause of the high prevalence of excess body fat in our society, and reductions in fat will not be a solution.

-Willett, "Is dietary fat a major determinant of body fat?"



Edit: secret ninja bonus!

Fatty acids are the chemical moieties that are thought to stimulate oral nutrient sensors, which detect the fat content of foods.... These data suggest that oral fatty acid hypersensitivity is associated with lower energy and fat intakes and BMI, and it may serve as a factor that influences fat consumption in human subjects.

-Stewart et al., "Oral sensitivity to fatty acids, food consumption and BMI in human subjects."

I remember seeing somewhere that tasting the flavour of fat triggers changes in gastric juices to improve its digestion.

[Conde Koma]

dammit Russ, I love it when you post, but can you translate it for laymen please? it sounds like I should be eating less carbs (which I guess means grains?) and eating more fats?

[TheRuss]

dammit Russ, I love it when you post, but can you translate it for laymen please? it sounds like I should be eating less carbs (which I guess means grains?) and eating more fats?

My main contention right now is that most of the conventional wisdom about saturated, monounsaturated and omega-3 polyunsaturated fats (particularly saturated) is misinformed, and that they are a good primary source of calories.

I do not currently have a broad enough base to make nuanced nutritional recommendations*, particularly in the context of activities where glycogen is crucial (like, say, martial arts). If you were a non-superheavyweight powerlifter or a bodybuilder, I'd say to look into a high-fat diet.



*Working on that, though.

[Ming Loyalist]

Eh, exercise covers over a multitude of dietary sins, but my own experience covers eleven months of enforced inactivity, so that's not the only answer.

yeah, i see that, but my point is that jack shouldn't be used as an example because he isn't like other humans.