A diet high in protein and weight loss are often linked in the media – is this link justified?
Challenging the myth that meat and dairy foods provide healthy dietary protein.
A recent article by their resident nutritionist in the NZ Listener (January 7-13 2012) claimed the “best way to lose weight” is to increase the amount of protein you eat to 20-25% of your energy consumption.
The article highlights the hypothesis of Massey University professor David Raubenheimer that humans will continue to eat any available foods until our pre-programmed appetite for a certain protein level is reached. He suggests that because we tend to favour foods high in carbohydrates (CHOs) and fats, we over-consume these in our attempt to meet and maintain our protein needs. This is an interesting and plausible idea, and various research studies are mentioned in support of it.
There’s no doubt that many Kiwis, as in other western cultures, consume high-sugar, high-fat foods such as pastries, cakes, dairy products and alcohol on a daily basis and that this is linked to an increasing obesity problem. We also know that short term food restriction diets do not produce long lasting results in weight reduction. How do we effectively address the linked issues of excess weight gain and inefficient dietary habits?
Studies quoted in the Listener article show the protein leverage hypothesis requires an accompanying and sustainable change to eating lower GI foods, to be effective in maintaining weight loss. The article examines our dietary nutrient ratios and suggests that protein leverage could reduce cravings for refined carbohydrates. This would presumably help the necessary shift towards low-GI Index foods, i.e. whole foods such as vegetables, fruit and whole grains that provide complex CHOs. Because protein needs would be satisfied sooner, the weight reduction would be achieved not only by changing the type of CHOs consumed, but also by an overall reduction in food intake.
While I appreciate that a change to these proposed nutrient ratios has been shown to improve weight loss outcomes, the long term health effects may not be so positive. Reducing excess body fat and eating predominantly low GI foods are both good pathways to better health. However the largest human nutrition study ever conducted has given us compelling evidence that eating such a high proportion of protein as proposed by Professor Raubenheimer leads to many of the modern diseases that reduce quality of life and life expectancy in today’s world. The problem is the type of protein we are encouraged to eat – animal protein. I’m concerned that the Listener article promotes animal products – meat and dairy – as top of its list of protein-rich food sources. Contradicting this recommendation, elsewhere in the article is mention of the well-established link between large quantities of red meat consumption and cancer risk. We can’t have it both ways. Good nutrition is that which supports universally good health outcomes, not selective ones.
Known as the China Study, a 20-year study involving 6,500 people in 65 rural counties in China exploded the myth that animal-based foods equate with good nutrition. The study, detailed in its director T. Colin Campbell’s 2005 book, concluded that a whole food, plant-based diet will not just prevent but also reverse chronic disease. Regular consumption of meat and dairy products was consistently shown to have the opposite effect.
The research also showed that no more than 5% protein was the optimum dietary intake for reversal of disease states. In study groups eating 20% protein – even when plant based – no reversal of existing disease occurred. These results were consistent. Proteins are necessary for growth; in fact promoting maximum growth is a function of efficient protein metabolism. This can lead to too much of a good thing. When we consume more protein than the body needs to achieve optimum cell growth, we tip the balance towards overgrowth. Cancer, obesity and other diseases of modern excess can follow.
All whole foods contain a combination of nutrients, principally water, proteins, fats and carbohydrates as well as a range of micronutrients. It’s therefore simplistic and not essentially accurate to describe one particular food as ‘a protein food’ and exclude another. Proteins are present in all foods to some extent, amidst a complex mix of nutrients that interrelate and contribute to balancing our health needs. The main differences in nutrient composition between plant foods and animal foods is that plants contain much higher levels of antioxidants, fibre and minerals, while animal-based foods contain much more cholesterol and fat.
By following a simple guideline of eating a whole food, plant-based diet with minimal intake of refined foods, added salt and added fats, all your nutrient needs including protein are met. It is not necessary to get complete proteins (i.e. all essential amino acids together) in every meal; rather they can be spread through the day. Proteins from plants are synthesised slowly and steadily by the body, contrary to the big impact meat proteins have on our metabolism. The low impact effect of plant proteins helps protect the body from the cellular toxicity that precedes all the main western diseases, including cancer, heart disease, diabetes, osteoporosis, Multiple Sclerosis and Alzheimer’s.
Attention to dietary intake is only one important factor in losing excess kilos and maintaining a healthy weight. Engaging in regular physical activity is another requirement. Attending to unresolved emotional issues that can become embodied in surplus layers of fat is a third significant factor for many people with weight problems. Changing the habits of a lifetime is a big challenge and best achieved step by step. It may involve challenging some myths that you’ve mistakenly taken on board as fact, influenced by cultural norms and the insistent voice of our primary producers and corporate advertisers.
By Carolyn Simon ND, DipMedHerb
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