High This, Low That

“The beginning of wisdom is the definition of terms”

- Socrates

 

High carb, low fat, moderate protein.  These are words to describe diets, but what do they mean?  The problem is that it really depends on how ‘high’, ‘low’ and ‘moderate’ are defined*.  For example: the Zone (30P:30F:40C) has been called a low carb diet, but is 40% carbohydrate really low?  Or is it simply ‘lower’ than the conventional guidelines and so should be described as a 'lower carb' diet. 

I’m going to propose some definitions for ‘high’, ‘moderate’ and ‘low’ to clear this up and base it on simplicity and some observations 

Protein

 

• ~10% protein is essentially the RDI for the average person, which is the sufficient intake to meet nutrient requirements of 97-98% of the population [1]
• Modeling has suggested that at least 15% protein is required to obtain sufficient micronutrients [2]
• The recommended protein intake for chronic disease is 15-25% [1]
• Protein intakes of 30-40% (depending who you speak to) and greater are thought to exceed the body’s ability to metabolise protein and/or get rid of urea
• The average protein intake in Australia in about 16.5% [3].  You could argue that protein intake would be slightly higher if 35% [4] of calories didn’t come from junk food (high in refined grains (~10%), added fats and added sugar) 

	Very Low	Low	Moderate	High	Very High
Protein	10±2.5	15±2.5	20±2.5	25±2.5	30±2.5

Fat/Carbohydrate

 

• If moderate protein is 20% then it would be nice if moderate carbs + fat = 80%
• There is an ongoing debate as to whether fat or carbohydrate is generally healthier.  At this point I don’t know, and probably no one does
• Eating ~0% fat or carbs is doable (no need for dietary carbs, PUFA requirement is extremely low), although very restrictive and probably not too healthy.  Anyway, it would be more accurate to refer to such a diet as zero fat/carb
• In PHD, the Jaminets calculated carbohydrate requirements (dietary or not, in the absence of ketosis) to be approximately 30% [5] 

	Very Low	Low	Moderate	High	Very High
Fat/Carbs	10±7.5	25±7.5	40±7.5	55±7.5	70±7.5

There are two main issues with this kind of classification: 

1.     A 1% increase in carbs from 47% to 48% magically results in the diet changing from a moderate carb diet to a high carb diet.  This is silly.  Think of the cut-off points not as thresholds, but as gradients

2.     These numbers are proportions, not absolute amounts.  The absolute amounts are more important to determine whether you’re getting enough of something.  In some circumstances the % can be misleading.  For example: an athlete on a low carb diet may eat more carbs than an inactive elderly person on a high carb diet like the dietary guidelines (45-65%) 

Finally ‘high’, ‘low’ and ‘moderate’ aren’t some judgment of whether a diet is ‘good’ or ‘bad’ 

* The field of diet is full of people using ambiguous labels to promote an agenda, for example: veg*ns say the SAD is high in animal protein and fat; mainstream dieticians say the SAD is high in red meat, SFA and salt; low carbers say the SAD is low fat and high carb; and everyone says the cliché of the SAD being high in sugar, fat and salt (if they choose their words poorly they might imply salt contains calories).  I heard a dietician say Australians eat a high meat diet and handed out some information suggesting we should eat 1 serve of meat per day.  You shouldn’t be surprised when you conclude that Australians eat a ‘high meat diet’ if you define ‘high meat’ as > 1 serve/day