Ketosis Carbohydrates and the Brain – Q&A

Question: I’ve been doing the CKD effectively. However, I have a major exam on Friday. Is there any effect on limited carbs on cognitive processes? Does limiting carbs ( 20g / day) have a negative effect or could it retard my performance on a major exam, i.e. MCATs, Series7, etc? Is there any study or suggestion you could give based on your research?

Answer: First a quick definition for anyone who isn’t familiar with the abbreviation: as discussed in the Comparing the Diets Series , a CKD refers to a cyclical ketogenic diet.  This is simply a diet that alternates between periods of very low-carbohydrate eating (typically 4-6 days) and very high-carbohydrate eating (1-3 days).  Dan Duchaine’s Bodyopus, Mauro DiPasquale’s Anabolic Diet and my own Ultimate Diet 2.0 are all examples of CKD’s.  My first book The Ketogenic Diet discusses CKD’s generally in mind-numbing detail.

Now back to the question: does ketosis negatively impact on cognitive function?  And the answer is one huge it depends.  Certainly early studies found that, in the short-term (first 1-3 weeks), low-carbohydrate diets tend to cause some problems.  For this reason short-term studies (usually a week long) tend to report decrements in a lot of things including cognitive performance.

Empirically, as well, many report fatigue, lethargy and a sort of mental ‘fog’ until they adapt to the diet (the brain adjusts to using ketones for fuel over those first 3 weeks).  I’d note that supplementing with sodium, potassium and magnesium seems to go a long way towards limiting or eliminating that feeling of fatigue.

So, for most I certainly wouldn’t recommend starting a very low-carbohydrate/ketogenic diet right before some major test or cognitive challenge.  Odds are it’s going to cause problems.

But what about someone who has adapted to being in ketosis. There there tends to be huge variance.  Some people are sort of neutral to it but I know of many who report far better brain functioning when they are in ketosis.  I couldn’t tell you the mechanism, this is just one of those self-reported things.  But it tends to be highly variable (and I can’t think of any studies that have examined cognitive performance after long-term adaptation to low-carbohydrate diets).


What’s Causing My Muscle Cramps – Q&A

Question: I have been following a very low-carbohydrate diet and taking the ephedrine/caffeine stack for the past 4 months.  Recently I have been having problems with cramping in the gym, I find that if I get too close to failure on a set, I get very bad cramps.  I’m drinking plenty of water and taking a multivitamin and I can’t figure out what’s wrong. Please help.

Answer: Cramping is unfortunately a very complicated topic and while many simple solutions are often thrown out, they don’t always seem to work.   Usually the culprit is issues with hydration per se or electrolyte levels; electrolytes are things like potassium, calcium, sodium and magnesium they are involved in transmission of the electrical signals in the body.  Hence their name.

I’d note that hydration and electrolyte levels are intertwined as the amount of water in the body affects the relative concentrations of the electrolytes in the body. So if there is more water present, the relative concentration of each of the electrolytes will be lower because the water will dilute them.  By the same token, if you are dehydrated, the relative concentrations of the electrolytes goes up.

Most ideas about cramping tend to focus on a single electrolyte, potassium was blamed for quite some time which is the basic origin of the ‘eat a banana to stop cramping’ idea.  Bananas are an excellent source of dietary potassium.

The problem is that cramping is way more complicated than this and can be related to all of the different electrolytes, not simply the absolute amounts of each but the interactions between them.  Fixing the problem often entails trying different things to figure out what’s causing the problems for a given individual.

Now, a potential issue specific to very low-carbohydrate diets (less than 100 grams of carbohydrate per day) and cramping per se is that these diets cause water loss.  As well, the water losses can vary massively from a low of perhaps 1-2 pounds up to 10-15 pounds in larger individuals.    As well, very low-carb diets cause electrolyte losses and this can cause cramping and fatigue.


Ketosis and The Ketogenic Ratio – Q&A

Question: Do you still believe in the ketogenic ratio for getting into ketosis?  I am having trouble showing ketones. Any tips? Sorry to bother you again but can drinking 2 gal of water per day dilute your urine so you don’t show ketones?

Answer: Ok, let me take these on one at a time.

In my first book The Ketogenic Diet, I talked about something called the ketogenic ratio (KR) which is an equation/concept used in the planning of ketogenic diets for epilepsy patients. The equation basically gives you the potential ketone producing potential of a given meal depending on the relative ketogenic or anti-ketogenic effect of the different macronutrients.

So the KR of a given combination of nutrients can be estimated with the following equation:


Click to See A Bigger Version


Protein turns out to be partially ketogenic (46%) and partially anti-ketogenic (58%), reflecting the fact that some amino acids can be made into ketones, while other are made into glucose).  Carbohydrate is 100% anti-ketogenic and fat is mostly (90%) ketogenic (the 10% anti-ketogenic is due to the fact that the glycerol portion of triglycerides, explained in A Primer on Dietary Fats, can be converted to glucose in the liver).


Carbohydrate Intake and Depression – Q&A

Question: I’m a 45 year old female. I currently weigh 221lbs. I’ve lost 30lbs in the last three months. My protein intake is roughly 120 to 130 grams per day.  I’m limiting my carb intake to 180 to 200 grams a day. I suffer from life long depression and I find that when I limit by carb intake I slowly slide into a depressed state after two or three months (it’s happening to me now). My sleep is disturbed, I develop anxiety I’m bitchy as hell and I’m dragging ass.  Is there a correlation between carb intake and production of neurotransmitters? If so, how can I eliminate the effect lower levels of carbs is having on me? Any information is greatly appreciated.

Answer: Dieting in general tends to lower serotonin in the brain and this can cause depression in susceptible people.  Interestingly, this effect seems to be more likely to occur in women than men (women being more susceptible to depression in general).  In my experience, low carbohydrate/higher proteins diets tend to be even worse in this regards for reasons I’ll explain now.

First and foremost, nutrient intake per se affects the production of neurotransmitters with the effects being both direct and indirect.

In a very direct way, specific amino acids are the precursors for specific neurotransmitters in the brain.  Tryptophan is a precursor for serotonin in the brain and the amino acid tyrosine (as well as phenylalanine which converts into tyrosine in the body) is the precursor for dopamine (and subsequently adrenaline/noradrenaline).

As an extreme example of this, researchers will sometimes use something called acute tryptophan depletion (accomplished by providing an amino acid solution containing all of the amino acids except tryptophan) to drastically lower brain levels of serotonin.  This is used to test various things but, among other things, it tends to cause acute depression in those who are susceptible.   However, this is a pretty extreme type of intervention, decreasing blood tryptophan levels massively (by about 80%); in dieting, tryptophan levels only drop by about 10%.


Lean Mass or Total Weight to Set Calorie Levels – Q&A

Question: Should I use lean body mass or total weight to set my caloric intake?

Or should I use goal weight?

Answer: First off let me address the second question, using goal weight.  With few exceptions I don’t recommend using goal weight to set anything for the simple reason that most people tend to pick a goal weight that is exceedingly unrealistic and this tends to make them set calories very strangely.  That is, unless someone sets a goal weight that is perhaps 10-20% below their current weight, using goal weight will tend to do odd things.  So I don’t recommend it.

As to the first question, as usual it depends and there are pros and cons to each method.   Let’s look at them and then I’ll explain why I tend to use total weight regardless.

Part of the complication is that total daily energy expenditure has several components to it; classically these included resting energy expenditure (REE), the thermic effect of food (TEF), and the thermic effect of activity (TEA).

Recently, interest in non-exercise activity thermogenesis (NEAT) and spontaneous physical activity (SPA) has also been generated based on the observation that people differ greatly in their ability to burn off excess calories through NEAT/SPA.  This topic is discussed in more detail in Metabolic Rate Overview.

And while a good deal of work shows that resting energy expenditure is related primarily to lean body mass.   It’s worth noting that lean body mass includes a lot more than muscle mass, something that is often forgotten.  I’m not aware of any work linking the thermic effect of food to lean body mass specifically.  The calories burned during activity tends to be related to total body weight (since you’re moving the entirety of you weight) and, depending on how active someone is, this can actually make up a fairly large portion of total energy expenditure.  So while part of daily energy expenditure is certainly related to lean body mass, not all of it is.