Remember those advertisements for cereals? “Start your day with the perfect breakfast!” was the usual catchphrase uttered. Although cereal has a history of being packaged as a health food, the truth is something else altogether.
You just need to take a trip down to your local grocery store to see the sheer variety of cereal products available for consumers – oatmeal, muesli, cornflakes, granola, etc. These foods are typically rich in carbohydrates and feature high in the glycaemic index (GI) to boot. Combine these two factors and you have a meal that's heavy in terms of glycaemic load (GL) while providing little to no value in terms of protein and dietary fat. That's never a good idea if we're looking for a sustainable nutrition plan that's ideal for body composition and health.
It has been well documented that excessive sugar is extremely damaging to health, never mind contributing to weight gain, however cereal that is deemed as ‘healthy’ can still contain a remarkable amount of sugar. For example, cereals such as Kellogg’s Nutrigrain, which contains 26.7g of sugar per 100g (1), and Nestle Fitness Fruits with 29.4g of sugar per 100g (2).
Glucose, not carbohydrates
Many people might object to my cereal-bashing, saying that “the body needs carbohydrates for energy”. That's a misconception; the body relies primarily on glucose for energy. While the body prefers to convert carbohydrates into glucose, this is due more to metabolic convenience. Protein and lipids, such as triglycerides can also be converted into glucose via a process known as gluconeogenesis. This process is slower compared to carbohydrate-conversion, but it provides a steadier flow of energy while preventing any major spikes in blood glucose levels.
Another worry of an excessive diet of carbohydrates is the fact that it can lead to a development of insulin resistance. Insulin resistance is one of the leading causes of obesity and type 2 diabetes; it makes sense to de-emphasise the presence of cereal products in your nutrition plan.
Of course, you may come across some cereal products that seem healthier than their more mainstream counterparts. They are usually touted as being low to no-sugar, high-fibre, full-grain alternatives. While some of these may in fact score lower in terms of their GI, their net carbohydrates content (total carbohydrates minus dietary fibre) still linger on the high side, putting their GL (GI/100*net carbs) in the higher regions. Frequently consuming meals with a high GL will only prove to be detrimental to long-term health and physique goals through the impairment of one's insulin sensitivity.
So is cereal healthy? Yes and no. Confusing as it may seem, such is the case with nutritional science. One must considers that there is always an element of human variability at play. Ultimately, one should consider their goals and tailor their approach to nutrition to fit said goals. Endurance athletes would obviously benefit from having a granola bar before training due to the nature of their sport. For the average person looking to get fit however, not so much.
Mayfield, J. (1998), Diagnosis and Classification of Diabetes Mellitus: New Criteria”, American Academy of Family Physicians. Retrieved from: http://www.aafp.org/afp/1998/1015/p1355.html
Mayo Clinic (n.d.), Type 2 Diabetes: Symptoms and Causes. Retrieved from: http://www.mayoclinic.org/diseases-conditions/type-2-diabetes/symptoms-causes/dxc-20169861
Kahn, B. B. & Flier, J. S. (2000), Obesity and insulin resistance, Journal of Clinical Investigation, 106(4), 473-481
(1) Source: www.kelloggs.com.au/en_AU/nutri-grain-product.html
(2) Source: www.nestlecereals.com/products/cereals/fitness-fruit