The FastDay Forum

[carorees]

Interesting point! The study was for 16 weeks, it would be interesting to know whether, if weight loss plateaued, a swap to the other diet would boost it again or result in an increase!

Maybe the idea of 'mixing things up' that I am currently proposing to people re feed day calories also applies to the macronutrient balance. This could also partly explain the boosting effect of an occasional big feast as usually those meals are high in fat and carbs which would be a change whether one was normally low carb/high fat or high carb/low fat!

How about this for a theory: we know about the concept of metabolic inflexibility whereby one's body is slow to switch to fat burning when we start on the fasting (or low carb) diet. Perhaps whenever we stick to a routine the body gravitates to being most efficient (i.e., burning the least amount of calories) on that routine, a change of routine shakes things up leading to inefficiencies and hence increasing the amount of calories burned.

Which image has the problem? I may have been logged into something allowing me access to the full paper - does that link work.

The different jargon in the two papers is indeed confusing. It arises in part because they are using simpler methods than a full insulin sensitivity clamping procedure.

In the first paper "Low insulin secretion" is determined by a smaller response to a glucose dose.

The second paper used fasting insulin levels to pre-select the subjects, then tested them with insulin modified intravenous glucose tolerance test to measure Si where Si = Insulin Sensitivity. The fasting insulin levels defined them as Insulin sensitive - low levels or Insulin Resistant - high levels. HOMA-R was also used to assess insulin resistance.

Note that the first paper did not find a statistical effect of baseline HOMA-R in other words insulin resistance was not statistically important, but the size of insulin response was.

"Insulin resistance" means organs don't respond to high levels of insulin as they should. "Insulin sensitivity" is the opposite of insulin resistance.

Insulin secretion is a measure of the response to a glucose challenge and does not of itself imply insulin resistance - it measures how much insulin is produced in response to glucose and a higher response will be more likely to produce reactive hypoglycaemia.

It all seems to be adding up to something we can advise:

If you are eating high carb/low fat and not losing weight change to low(ish) carb/high fat. Conversely, if you are eating low carb/high fat and not losing weight, change to the reverse style. Using the mfp app/website will give an indication as to what the current balance is.

Comments?

"If you are not losing weight then reduce your overall calorie intake" should surely be the first response - in both studies even the "inappropriate" diet choice gave a weight loss. In the second paper the weight loss of the inappropriate combinations matched the expectation from the calorie deficit.

Some qualitative indicators could perhaps be used to steer people to the most likely appropriate diet composition ? Diabetes is an obvious one, reactive hypoglycaemia tendencies would be another.

Please remember that "low carb" in these studies is "a bit less carb" really, but in general I don't object to the idea of trying something different if a chosen approach is failing.

Perhaps a diet high in carbs and low in fat means that we give the body no extra fat to store? Or did I over-simplify it?

Perhaps a diet high in carbs and low in fat means that we give the body no extra fat to store? Or did I over-simplify it?

I think you did, the diets are hypocaloric ie have a calorie deficit so there's nothing spare to store and in all cases there was weight loss.

[carorees]

Carbohdrates are converted to fat if in excess so you still have to eat fewer calories than you burn.

@PhilT: I meant to say of course "if you aren't losing weight despite being fairly certain you are not overeating."

I would put it stronger than that - "First try reducing your average calories per day by 500 for one month, this should give you a weight loss around 4 lbs / 2 kg. "

If this does not give the required result and your diet is high in carbohydrates (over 50%) try switching to a diet with 40% or less carbohydrate and increased fats / oils. On the other hand if your diet is low in carbohydrates - 40% or below - then a switch to higher carbs and lower fat may be beneficial.

For illustration, in a 2000 calorie diet 40% carbs is 200 grams, 60% is 300 grams. The carbs includes starches and sugars from all sources including fruit and refers to the carbohydrate content rather than the weight of the carby food.