In a previous article, I summarized the current state of scientific knowledge regarding individual carbohydrate tolerance. There is exciting, emerging research in this area, but from a clinician’s point of view, it is already clear that differing amounts of the macronutrients (protein, carbohydrates and fats) affect individuals differently.
While there are best practice guidelines for various desired outcomes, there is a large degree of individuality between the prescriptions for individuals. This variability is dictated by practitioners’ biochemical individuality, metabolic typing, or other circumstances. At this point in time, there is no accepted way to determine the macronutrient ‘tolerance’ of an individual, except in those cases where a specific diet is required due to a disease or disorder (such as a ketogenic diet for epilepsy).
What Determines Your Carb Tolerance?
In clinical practice, carbohydrate intake is often adjusted the most, because of its non-essentiality.1 Because carbohydrate is not essential, and yet can be extremely beneficial, we need to be able to evaluate better what the differences in response to this macro may be. Due to its nature as an almost exclusively fuel-providing substrate, we know that carbohydrate intake rests upon two major factors:
- The activity level of the individual: Including latent activity from habits, nervous and ‘constitutional’ behaviours, work-type, and exercise intensity, frequency, and volume.
- The metabolic tolerance to carbohydrate: Dependent on genetic predisposition, exercise/activity levels, and dietary and medical history, especially where these factors may contribute to a tendency towards insulin resistance.
The difficult part for anyone is to try to figure out their unique tolerance to the macronutrients. One could begin by counting calories and macronutrients and adjusting these to attempt to find an optimal range of intake, but this is often tedious, ultimately unsustainable, and is unnecessary for most people. On the other hand, a ‘step-wise’ restriction of certain food types can be enormously helpful in finding a level of carb intake that meets your metabolic tolerance and activity-based requirements.
Do the Simple Things First
But before we even think of getting down to the minutiae of nutrition, we can make great strides toward achieving our health and performance goals simply by focusing on three simple words: natural, whole, and unprocessed.
People overcomplicate nutrition and rush into using diets with extreme restrictions or excessive supplementation, when minor changes applied with consistency will give the best long-term results. Small and consistent changes are also easier to implement and integrate into your daily routine, and can more easily become positive habits that ‘stick.’ Conversely, doing more than what is necessary to achieve your goal is a wasted effort and can be counterproductive in the long-term.
A good way to start is to simply eat a diet that is at least 80% natural, whole, unprocessed food, ad libitum (in other words, eat as much as you desire). Don’t get me wrong, I don’t say this because I’m some naturalistic devotee. More so, the emerging evidence simply points to ‘natural’ (however abused the word has become) diets offering benefit without the need for calculated calorie restriction or macro manipulation. While critics may point to a relative paucity of research on diets that emphasize whole, unprocessed foodstuffs (such as the paleo diet), there is emerging and compelling evidence for the beneficial effects of real-food diets.
If the only thing you do to your diet is eat real, natural, unprocessed food, the rest may take care of itself.
The Emerging Science of Paleo Diets
Paleo, as an example, while often derided by orthodox dieticians and medical practitioners, has a growing body of evidence which suggests compelling benefits.
Cardiometabolic Risk Factors
- A randomized, controlled trial featuring nine men and 25 women found that a paleo diet resulted in lower blood pressure, cholesterol, triglycerides, and higher HDL cholesterol than the reference diet over two weeks. No differences were noted for intestinal permeability (‘leaky gut’), inflammation or salivary cortisol (a marker of stress).
- A randomized cross-over trial featuring ten men and three women demonstrated that paleo diets have a lower glycemic index and are lower in total energy compared to a diabetic diet. The paleo diet resulted in lower HbA1c (a measure of average blood sugar levels), triglycerides, blood pressure, and higher HDL cholesterol.
In a two-year, randomized, controlled trial, post-menopausal women lost more fat at six months and had lower triglycerides at six and 24 months.7 Ten healthy post-menopausal women ate ad libitum (eat as much as you want) on a paleo diet for five weeks. Average calorie intake was reduced by 25%, and average weight loss was 4.5kg, along with reduced waist and hip circumference, blood pressure, fasting glucose, cholesterol, triglycerides, and LDL cholesterol (fat in the liver – a marker for metabolic disorder was also decreased).8
Diets that emphasize real, whole foods are also likely to:
- Provide increased amounts of a complex array of both primary and secondary nutrients
- Provide prebiotic, gut-supporting fibers and resistant starches without increasing glycemic load in a disproportionate manner
- Reduce glycemic load in total
- Preserve fat quality
- Provide ample amounts of all macro- and micro-nutrients
- Aid auto-regulation of calories
Eat Well Before You Fiddle with Numbers
The absolute priority for any change in diet should be to focus initially on the quality of food eaten, not just quantities. Many people will find that simply applying a greater focus to eating a diet that is based almost exclusively on natural, unprocessed foods will not need to be any more restrictive or prescriptive. Take a look at your plate next mealtime. Is it covered by at least 80% natural, unprocessed food?
If your goal is simply to be healthy, perform well, and be in great shape, save yourself the stress and hassle of calorie counting. Unless you’re looking to beat Usain Bolt’s record later in the year, you may get what you desire by simply focusing on the compendium of foods you eat, rather than fastidiously logging food diaries and weighing your foods.
Simplicity rules, and that should be the place to start. If you need to fine-tune further, that option is always available to you.
Beyond the marketing, there’s a reason most diets work:
1. Westman EC. Is dietary carbohydrate essential for human nutrition? The American Journal of Clinical Nutrition. 2002;75(5):951-3.
2. Bligh HF, Godsland IF, Frost G, Hunter KJ, Murray P, MacAulay K, et al. Plant-rich mixed meals based on Palaeolithic diet principles have a dramatic impact on incretin, peptide YY and satiety response, but show little effect on glucose and insulin homeostasis: an acute-effects randomised study. The British Journal of Nutrition. 2015;113:574-84.
3. Jönsson T, Granfeldt Y, Lindeberg S, Hallberg A-C. Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes. Nutrition Journal. 2013;12:105.
4. Jonsson T, Granfeldt Y, Erlanson-Albertsson C, Ahren B, Lindeberg S. A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease. Nutrition & Metabolism (Lond). 2010;7:85.
5. Masharani U, Sherchan P, Schloetter M, Stratford S, Xiao A, Sebastian A, et al. Metabolic and physiologic effects from consuming a hunter-gatherer (Paleolithic)-type diet in type 2 diabetes. European Journal of Clinical Nutrition. 2015.
6. Frassetto LA, Schloetter M, Mietus-Synder M, Morris RC, Jr., Sebastian A. Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet. European Journal of Clinical Nutrition. 2009;63(8):947-55.
7. Mellberg C, Sandberg S, Ryberg M, Eriksson M, Brage S, Larsson C, et al. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. European Journal of Clinical Nutrition. 2014;68(3):350-7.
8. Ryberg M, Sandberg S, Mellberg C, Stegle O, Lindahl B, Larsson C, et al. A Palaeolithic-type diet causes strong tissue-specific effects on ectopic fat deposition in obese postmenopausal women. Journal of Internal Medicine. 2013;274(1):67-76.