Our dilemma here is that there are really two opposing effects of meat and other animal proteins. One is to raise insulin which tends to cause weight gain, The other is to slow gastric emptying, increase satiety and tends to cause weight loss. Which is the stronger effect?
One of the largest association studies of the recent past has come from analysis of the data by combining three very large cohort studies – the Nurses Health Studies I and II as well as the Health Professional’s Follow Up study. Looking at this combined data, comparison was made between specific foods and and the risk of obesity. While this was not a randomized trial, it still contains vast amounts of useful data. “Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men” was published in the New England Journal of Medicine in 2011.
One of the most important things that the researchers did was to look at specific foods. The past few decades had seen the rise in ‘nutritionism’ whereby foods were reduced to classification into ‘carbs’, proteins and fats. However, that does not even begin to capture the complexity of food science. An avocado, for instance is not simply 88% fat, 16% carbohydrate, and 5% protein with 4.9 grams of fibre. But this sort of nutritionism is how avocados became classified as a ‘bad’ food for years due to its high fat content only to the reclassified today as a superfood. (Useful online tool for this sort of useless thing here). While kind of fascinating, there are hundreds of nutrients and phytochemicals in foods that affect our metabolism not captured by this sort of simplistic analysis.
This is the sort of useless thing, by the way, which goes into food labels which kind of explains why they don’t really make any difference. I imagine that nutritionism really got going during the ‘low fat’ craze of the 1970’s where we imagined that we could explain the effects of all foods based on 3 macronutrients. First, we thought that all fat is bad. Then all carbs were bad. The there were good carbs and bad carbs. Then there were good fats and bad fats. Next there will be good proteins and bad proteins (animal vs plant for instance). The truth is that food resists such easy classification. We also make this sort of artificial distinction for types of food – fruit for example. Banana is a bad fruit and berries are a good fruit. This was based on a notion such as the glycemic index, or the amount of fat, or the amount of sugar.
Following 120,877 men and women over 12 to 20 years, the researchers calculated the association between intake of specific foods and weight gain. Overall the average weight gain over any 4 year period was 3.35 pounds – pretty close to the 1 pound per year that is often estimated. While this may not sound like much, over 40 years, say from age 20 to age 60, that will result in 40 excess pounds transforming the 160 pound average person into a 200 pound pre diabetic patient.
It is important to remember that an association study like this cannot prove causation. However, one of the strengths of this study is to be able to look at long term results – something that randomized trials tend not to do. Because weight gain accumulates over decades, a short term trial of several years may not tell us what we ned to know.
However, it is still interesting to look at the data here. It is easy enough to understand why potato chips and french fries may be fattening. They are both highly processed carbohydrates that raise insulin and glucose significantly. For the same reason, sweets and desserts, and refined grains are all highly associated with obesity. Indeed, it would hard to find anybody who would argue that potato chips, desserts and white bread are not fattening.
But there is also a strong association between processed meat, unprocessed meat and butter and obesity. Since these are not carbohydrates, one may assume that they are not fattening. But they are. Once you realize that protein also stimulates insulin, it begins to make some sense that these foods may also lead to obesity. But it is the meats and not the dairy so much that leads to obesity despite the fact that dairy proteins stimulate insulin to a much higher degree. The problem here may be a quantity of meat versus dairy ingested as we explored in the last post.
There are also foods that are associated with a lower risk of obesity – for instance, nuts and vegetables. This seems straightforward. Both are low in sugars and very high in fibre. Both effects will tend to lower insulin and protect against weight gain. But whole grains and fruit are also protective. A shock to Atkin’s enthusiasts, it appears that the high fibre in these foods may be protective.
Among beverages, sugar sweetened beverages and fruit juice are associated with obesity. Not a surprise – both are very high in sugar and very low in fibre. Skim milk may have a slight association, but whole milk does not. The higher milk fat may be the protective agent here. Diet soda is protective, but I have my doubt whether this is a true effect or whether it merely reflects that fact that these are people that are trying to lose weight.
It become much easier to understand the graph when you consider that all the foods that tend to cause weight gain tend to raise insulin. Those that tend to protect against weight gain tend to contain protective factors – fibre, fermentation (yogurt), and fat.
Here then, may be the the clue to the final unravelling of the Atkin’s diet. Originally envisioned as a low carbohydrate, high fat diet, it evolved into Atkins 2.0 in the 1990s. While still low carbohydrate, the low fat craze turned the Atkins reboot as a low carb, high protein diet. Atkins enthusiasts turned away from real food to Frankenfood creations like protein milkshakes sweetened with fructose, meal replacement shakes and protein bars.
Pharmaceutical companies, like Matt Taibbi’s vampire squid that jams its blood funnel into anything that smells like money, were only too happy to create new nutritional products to cater this new craze. Boost. Ensure. Optifast. Slimfast. Have you ever read the ingredients of these meal replacements? It would horrify you. Milk protein, fructose, canola oil, soybean oil and a multivitamin. Does this sound good to you? Or check the ingredients of Atkins Nutritionals bar. Chocolate flavour layer, peanut butter flavour layer, glycerin, protein blend, cellulose etc. There is more friggin’ glycerin than protein!!!!
Not recognizing that not all carbohydrates are inherently fattening, they also turned away from many delicious and nutritious fruits and vegetable. This made the diet hard to tolerate and sure enough, the compliance to the diet turned out to be very low. This was not a diet that you could follow for life, despite what many claimed. Dr. Atkin’s New Diet Revolution was finished.
Continue here with Red Meat Dilemma II – Hormonal Obesity XXVII
Start here with Calories Part I – How Do We Gain Weight?
See the entire lecture – The Aetiology of Obesity 3/6 – Trial by Diet
By The Fasting Method
For many health reasons, losing weight is important. It can improve your blood sugars, blood pressure and metabolic health, lowering your risk of heart disease, stroke and cancer. But it’s not easy. That’s where we can help.
By Jason Fung, MD
Jason Fung, M.D., is a Toronto-based nephrologist (kidney specialist) and a world leading expert in intermittent fasting and low-carb diets.