Living low carb? Here’s how to find your level of carb tolerance

Article by Cliff Harvey ND, PhD (c).

A lot of people I know thrive on high carbohydrate diets. On the other hand, even more of my friends thrive on low carbohydrate diets, and a whole bunch are somewhere in between…and are also getting great results!

So, where does that leave us? How do you know what you should eat?

Often people give us advice based on what works for them. BUT just because a diet works for one person, doesn’t mean that it will work for everyone. A diet that works for you may or may not be a diet that works for someone else.

A few attempts have been made to determine how much protein or fat or carbohydrate someone should eat, based on questionnaires, blood type, or other physical characteristics. Unfortunately, most of these just haven’t panned out. For example, metabolic typing1has failed to help improve fat-loss,2 blood type diets3 don’t work,4, 5 and somatotype (used to indicate relative ‘fatness’, muscularity, and linearity of the physique) simply hasn’t been studied with respect to whether someone responds better to higher or lower amounts of carbs.

There is evidence though that someone’s relative level of insulin resistance might affect whether they respond better to a high, or low, carb diet.6-9 Insulin resistance and insulin sensitivity describe how receptive we are to the effects of insulin the body’s primary ‘storage hormone’. When we are more sensitive to insulin we can lose fat more easily and are less likely to gain it. These findings are very preliminary but are important because of the growing rates of metabolic disorder and ‘pre-diabetes’, which are disorders of insulin resistance.

There are a few problems with trying to determine your diet based on insulin resistance though. The first problem is knowing whether you’re insulin resistant. The second is just how insulin resistant you are, and thirdly, restricting carbs to match this is still guesswork at best and is also likely to involve lots of calories and ‘macro’ counting…which isn’t going to be much fun.

I’m currently performing randomised, controlled trials to evaluate several markers of carb-tolerance, and within the next few years, we hope to have a much better idea of how to more accurately determine, in the clinic, whether someone should be following a lower- or higher carbohydrate diet. But in the meantime, you might be thinking ‘Well that’s great Cliff…but what the heck do I do now?’

A strategy I outline in The Carbohydrate Appropriate Diet book10 is to use a step-wise approach to carb-restriction to determine your unique tolerance. If you are doing fine now, eating loads of carbs, and you’re lean and your bloods look great (low triglycerides, good HDL and LDL ratios, normal-low HbA1c) then stick to what you’re doing!

But, if you’re not as lean as you’d like to be, or your bloods (especially HbA1c and triglycerides) are elevated you can reduce your carb intake, step-by-step, by eliminating certain carb foods, one-by-one. For example, you can start by simply avoiding all processed and added sugars for a couple of weeks, if you are getting great results from this, stick with it! If you aren’t losing weight or seeing any changes (over longer periods of 3+ months) in your blood results, then you can take a step up, and eliminate gluten grains, or grains in general, and so on, until you find the level of carb intake that works best for you.

And remember that once you find a good level, you should stick with it until your goal is achieved but once you have achieved the desired level of leanness or great changes in your blood markers, you can ‘step down’ and start to reintroduce, again step-by-step, some good quality carb foods. Some people will end up being very low-carb using this strategy, others will find that a moderated carb diet gives them all the results they’re after, without the stress and worry of calorie counting.

Figure 1. A step-wise approach to carb restriction

Figure 1. A step-wise approach to carb restriction

BUT, we need to take a step back first and make sure that eat least 80% of what you see on your plate, at any given meal, is natural, whole and unprocessed food. We have observed in our clinical trials that when people focus on whole foods (and eat at least 6+ serves of veggies per day!) they have a remarkable ability to ‘autoregulate’. In other words, they tend to not overeat, and they eat appropriate amounts of carbs, fat and protein for them without even trying to. And that is the key…

At the end of the day, a diet that helps you to eat an appropriate number of calories, while still being satisfied, and is easy to implement in your daily life is the one that is best for you, and this is not necessarily the diet that is supposedly the best for your body! So, start with natural and then find your Carb-Appropriate level by using the step-wise process outlined above.

About Cliff Harvey

Cliff Harvey is a registered clinical nutritionist and naturopath. He has been coaching people ranging from world champion athletes, through to the chronically and acutely unwell, to perform at their best, since the 1990s. Cliff is the founder of the Holistic Performance Institute, a private post-tertiary college providing graduate qualifications in holistic, evidence-based nutrition, and is a doctoral candidate and researcher in metabolic adaptation and ketogenesis at AUT University. He is also the author of six books including his latest release The Carbohydrate Appropriate Diet.



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