Paleo and HIIT: A Combination Not Made in Heaven

​A Paleolithic diet appears to undermine the positive effects of a Crossfit-based high-intensity circuit training exercise program.

Much of the low carb and modern Paleo reasoning revolves around insulin, which is branded the “root of all evil” by Paleo enthusiasts and bloggers, who unanimously claim that carbohydrates raise Insulin levels, hence why we should stick to a high protein and fat diet, and little-to-no carbs to prevent a pike in Insulin.

We know that for more than half a century, that if you give a person a steak without any carbs, starch or sugar, the insulin level rise.

A study conducted by SUKKAR, MY. HUNTER, WM.  and PASSMORE, R. from the Department of Physiology, University of Edinburgh and the Medical Research Council Clinical Endocrinology Research Unit (Edinburgh), monitored plasma levels of Insulin (and growth hormone) measured over a 6-hour period in ten normal subjects, (a) fasting and resting, (b) after a protein meal and resting, and (c) after a protein meal followed by 2 hour moderate exercise. This is what they concluded:

“It is clear that a protein meal, whether directly or indirectly, causes enhanced Growth Hormone (GH) secretion when compared with levels during a control fast in the same subjects.”

“Our studies confirm that these changes do occur, as increments over the fasting pattern, under more carefully controlled conditions and after protein taken in an amount which is frequently contained in an ordinary meal. The insulin response after protein is prolonged and could be a consequence of the equally prolonged elevation of amino acid levels in the blood.

The value of increased insulin secretion after a protein meal may lie in its ability to enhance the tissue uptake of amino acids.”

“First, even small increases in plasma insulin levels could, if unresisted, block FFA (Free Fatty Acids) release. Secondly, a series of changes in carbohydrate metabolism might be expected. These include accelerated entry of glucose into cells, especially in muscle and adipose tissue and in the liver, increases in both fuel storage (Lipogenesis and Glycogenesis) and in the rate of glucose utilisation. […] The metabolic effect of insulin on the fuel balance is then an increase in carbohydrate and a decrease in fat utilisation.

The fourth significant finding in this study is that the muscular activity markedly diminishes the insulin response to a protein meal. Plasma insulin levels also fall rapidly in exercise taken during the absorption of glucose (unpublished results). “

“Certainly insulin would appear to have small importance at this time, for exercise enhances glucose uptake without the agency of insulin. Muscular work may give rise to Hypoglycaemia, which is not mediated by insulin. Exercise reduces the insulin requirements in diabetics. Finally, FFA are now established as a major source of energy for working muscle and the release of insulin during exercise would both inhibit fat mobilisation and enhance lipogenesis, and so reduce the availability of fat as fuel. In previous studies in which protein was eaten in divided amounts during the walk (25 g. every 30 min.) there was markedly increased HGH secretion over that found during walking while fasting. Under these conditions plasma insulin (which was not measured) might be expected to remain elevated. The very high GH values can then be seen as necessary for providing some fat mobilisation even in the presence of raised insulin levels.”

Even though this was done on a very small sample group of people, the findings all lead toward the same results: not only regular intake of protein increase Insulin levels when accompanied to exercise, but also the mobilisation of fatty acids in the muscle, as to give the muscles enough energy to function, therefore protein intake does have a direct effect on Insulin.

This was actually the tip of the iceberg. In 1997, the Insulin Index of Foods was created, using 38 of the most common foods, in a 240 kcal portion, comparing spike in insulin and the low GI of those foods, and concluded that:

“Some protein and fat-rich foods (eggs, beef, fish, lentils, cheese, cake, and doughnuts) induced as much insulin secretion as did some carbohydrate-rich foods (e.g. beef was equal to brown rice and fish was equal to grain bread).”

“Fish, beef, cheese, and eggs still had larger Insulin responses per gram than did many of the foods consisting predominantly of carbohydrate.”

“The results confirm that increased insulin secretion does not account for the low Glycaemic responses produced by low-GI foods such as pasta, porridge, and All-Bran cereal. Furthermore, equal-carbohydrate servings of foods do not necessarily stimulate insulin secretion to the same extent. For example, […] servings of pasta and potatoes both contained ≈50g carbohydrate, yet the IS [Insulin Score] for potatoes was three times greater than that for pasta. Similarly, porridge and yogurt, and whole-grain bread and baked beans, produced disparate ISs despite their similar carbohydrate contents.”

Yet, it seems there is no difference when it comes to meat, indistinctly beef, chicken or pork nearly have the same IS:

Michael Greger, MD, was even more categorical in his NutritionFact.org, volume 22 (2014)1, using the diagram shown below, commenting:

“What do you think causes a larger insulin spike, a large apple and all its sugar, a cup of oatmeal packed with carbs, a cup and a half of white flour pasta, a big bunless burger—no carbs at all, or half of a salmon fillet?
The answer is the meat. Thus, protein- and fat-rich foods may induce substantial insulin secretion. In fact meat protein causes as much insulin release as pure sugar.”

“If they really believed insulin in the root of all evil, then low carbers and paleo folks would be eating big bowls of spaghetti day in and day out before they’d ever touch meat.

Yes, having Hyperinsulinaemia, too high levels of insulin in the blood, like type 2 diabetics have, is not a good thing, and may increase cancer by like 10%. But if low carb and paleo people stuck to their own theory, it it’s all about insulin, they would be out telling everyone to go vegetarian, as vegetarians have significantly lower insulin levels even at the same weight. It’s true for Ovolactovegetarians. It’s true for Lactovegetarians and vegans. Meat-eaters have up to 50% higher insulin levels."

His conclusion is even more partial:

“The paleo movement gets a lot of things right. They tell people to ditch dairy and doughnuts, eat lots of fruits, nuts and vegetables, and cut out a lot of processed junk. [But take] a bunch young healthy folks [and] put them on a Paleolithic diet along with a Crossfit-based, high-intensity circuit training exercise program. Now if you lose enough weight exercising you can temporarily drop your cholesterol levels no matter what you eat.”

“Ten weeks of hard core workouts and weight loss, and LDL cholesterol still went up. And it was even worse for those who started out the healthiest. Those starting out with excellent LDL, under 70 had a 20% elevation in LDL, and their HDL dropped. Exercise is supposed to boost your good cholesterol, not lower it. The Paleo diet’s deleterious impact on blood fats was not only significant, but substantial enough to counteract the improvements commonly seen with improved fitness and body composition. Exercise is supposed to make things better. Put people instead on a plant-based diet and a modest exercise program—mostly just walking-based, and within 3 weeks can drop their bad cholesterol 20%, and their insulin levels 30%, despite a 75-80% carbohydrate diet whereas the paleo diets appeared to negate the positive effects of exercise.”

A Palaeolithic Diet might, therefore, not be adapted to intensive Exercise, such as HIIT, as it may raise LDL Cholesterol, and lead to Atherosclerosis. Perhaps, looking at Paleo as a way to obtain a healthy weight, which interacts directly with fitness goals, may not be the answer. Loosing weight and building muscles cannot go hand-in-hand. 

Remember: 100 g of steak (or other meat) raise insulin levels as much as 100 g of pure sugar!1


So, now imagine if you do not exercise at all, not very mindful about what you eat, and snack often on very sugary foods. When do you think your blood insulin level ever drops? Perhaps, the most important is to realise that it will lead to obesity, insulin resistance (the cell become resistant to glucose, because the insulin receptors are switched off) and type-2 Diabetes.

---

Sources:

Sukkar, MY. Hunter, WM. Passmore, R. (1968). The Effect of a Protein Meal with and without subsequent exercise on Plasma Insulin and Growth hormone. Experimental Physiology and Cognate Medical Sciences. 53 (2), pp.206–217.

Holt, SHA. Brand Miller, JC. Petocz, P. (1997). An insulinindexof foods:the insulindemand generatedby 1000-kJ portions of common foods. The American Journal of Clinical Nutrition. 66 (1), pp.1264–1276.

1 Available at: http://nutritionfacts.org/video/paleo-diets-may-negate-benefits-of-exercise/?utm_source=NutritionFacts.org&utm_medium=email&utm_campaign=6e7cac940c-RSS_VIDEO_DAILY&utm_term=0_40f9e497d1-6e7cac940c-23347613