it's that time of year again

At the beginning of each year I treat myself to a week or so of study in something new to me. The intention is to learn enough that I might not embarrass myself asking questions afterwards ...  This year I looked at the interplay between food systems, restaurants and transportation in 19^th century America.  It turned out to be a richer topic than I had imagined leading to a few rabbit holes.  One was the emergence of the thin body type as desirable.  First in men and twenty or thirty years later in women and its connection to the concept of muscular Christianity and the emerging middle class in America and England.  Just as interesting was the realization that colonial America offered an abundance of food to immigrants (slaves not included).  There was an easy self-sufficiency that didn't exist in Europe at the time - at least not for the commoner.  In the 17^th and 18^th century the English spoke about the luxury of dietary self-sufficiency as self governance and that was probably the meaning of the term in America at the time of independence.  I didn't pursue those lines very far as there was other fascinating game at hand, but perhaps I'll return.  I was primed to think about some of our habits that would seem odd to those before the Civil War...

 

With the New Year many have started diet and exercise programs and almost as many won't make it more than a month or two. As I learn more about metabolism I tend to separate diet from exercise. Exercise by itself is terrific and is now considered a powerful drug with a mostly positive impact and few side effects. It is frequently prescribed, but many of us tend to under-medicate. We also misjudge its impact on weight maintenance.  It takes a large amount of exercise to burn enough calories to lose weight, but we tend to reward our hard work with goodies or otherwise subconsciously eat more. Unless you are an athlete in training you probably can't outrun your fork. Other than noting any calorie counting scheme that includes exercise is probably suspect, I'll concentrate on diet.¹

 

There are historical treatments that point out when thin became popular in Western Europe and the US and how the diet industry began.  I've seen feminist pieces on the negative issues associated with body images, but I haven't seen a cultural examination of diets and fad diets. Many of the plans seem to be based on the epic heroic story arc with someone starting out suffering to the point where they start on a quest. The quest usually involves wander and sometimes invokes deep cultural myths (but rarely science).   After difficult battles it ends with success and happiness.  This is sometimes communicated with religious fervor. The cultural myths may be mirrors to deeply seated beliefs. Sometimes there is a retreat to earlier times which are painted as carefree and healthy. Modernity and 'chemicals' are foes to be avoided - if we can only return to these simpler times all will be well.  Never mind that people rarely made it to thirty before the agricultural revolution and everything organic is chemical based.

 

This being a modern age, it is often assumed  prescriptions for the best healthy diet exist.  A numerical prescription for a healthy diet requires a predictive model that is appropriate for individuals.  Unfortunately we aren't even close.   There are thousands of studies on some food, nutritional element or diet, but most of them are limited and don't reach the entry level of being considered solid science.  Human nutrition studies are expensive and many are funded by companies with clear conflicts of interest.  A few are raised to public attention by undeserved publicity.  Fish oil was highly touted as healthy with millions buying and using the product. The problem was that the excitement was based on a single weak study made a few decades ago. The result seemed impressive so it was publicized. When examined carefully it became clear that while the benefit was real, it only existed for people who were mostly Inuit and may be detrimental to other groups.  Superfoods come and go yearly and there seems to be a fad diet of the year.  Some larger trends - paleo comes to mind - have no solid basis in science and seem to be based on a mixture of myth and even politics.

 

The science situation is difficult. The type of experiments you would like to do where you start infants on vastly different diets and follow them to old age while holding all environmental conditions the same as other trial groups are impractical and unethical. Data is taken on massive longitudinal studies, but it takes at least thirty years to begin to get information and much of the data is self-reported and of poor quality.  Furthermore individual metabolisms differ greatly and are now known to be influenced by our personal micro-biome and perhaps even the epigenetics coming down from our grandparents. Metabolic measurements can be made, but the precision is not terribly accurate. Try counting calories some time. I guarantee you won't get within twenty percent of reality. Even then the caloric assignment for food components is a hundred years old. Even though it is known to be flawed, there isn't anything much better that would make a difference.

 

So is there any hope?

 

While the quantified person approach is a bit silly at this point as nutritional models are too primitive there is something very useful.² Many studies are large enough and well enough understood that metastudies lead to qualitative and semi-quantitative results. These have been relatively stable for a few decades, but are refining and becoming more accurate with time. While I'm a doctor, I'm not the right kind of doctor to offer dietary advice. So with that caveat here's a summary of the consensus of those who are expert:

 

° don't over-eat and try not to exceed a desirable weight range in your youth and middle age.

° eat a lot of vegetables and fresh fruit

° whole grains and legumes are good

° avoid unsaturated and trans-fats

° aovid excessive salt

° avoid excessive butter

° if you eat meat, do it in moderation (Mediterranean diets average on the order of than two ounces of meat a day)

° stay away from excessive sugar.

° if you drink, do it in moderation

° where possible, prepare your own food so you have knowledge and control of its contents

 

A few dietary types have emerged as statistically leading to populations that enjoy good health outcomes into their 80s. Mediterranean and vegetarian diets appear to be good over large populations. Strict adherence to a particular diet is probably unimportant and unadvised given the quality of current models. If you can find one that incorporates most or all of the bullet points that is easy for you to maintain, go for it. There are a few behaviors that seem to team up with the nutritional elements to lead to good outcomes. 

 

° try to lead a low stress lifestyle

° value friendships

° get enough sleep

° get enough exercise

 

Not that this is easy given many of our lifestyles. If you're overweight getting back into a healthy weight range can be difficult. Keeping it off for the long term makes losing weight in the first place look easy. But the fad diets are wastes of your time and some can even be dangerous. If you want change, just go with something simple. The expert view seems to be getting away from the idea of healthy nutrients and getting to having a combination of foods that gives you the proper mix of nutrients. There will be many paths to achieve the goal.

 

Exercise is a different matter. Just find something you like to do and just do it. There is evidence that as little as a half hour a day of fast walking bestows major benefits. Countries like Denmark and the Netherlands partly fund their bicycle infrastructure from healthcare funds. There is good evidence that getting enough active transport, walking or cycling, leads to a higher quality of life in middle and late age. If a large enough segment of the population participates, healthcare costs drop.

 

If you are trying to lose weight you can be pseudo numerical. You won't be making accurate assignments to what you eat, but if you are internally consistent and weigh yourself a few times a week (psychologically Wednesday turns out to be best if you do it once a week), you can make adjustments that will fit your metabolism.³ Regular use of a scale is a powerful tool.

 

But in the end I suspect movement towards the healthier eating styles that are being identified will be glacial.  We love good stories and the drama of the heroic narrative is a siren call and part of popular culture.  

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¹ Energy expenditure from exercise is poorly measured. Smart watches, Fitbits and exercise equipment - unless calibrated for you in laboratory conditions - are rarely better than 20% accurate and repeatability is poor. They can be useful for those who like to keep track of progress, but the connection to weight management is complex and non-linear. It appears that large amounts of exercise make the body more efficient and do not lead to weight loss - at least not as much as one would expect doing a simple tabulation.  It should also be noted that no one knows how much exercise is needed. There are some good base level estimates, but it is certainly not true that doing two times as much as some basic level is two times as good for you. This is seriously complex so unless you like to keep track of numbers and try to make them increase because you like to see numbers increase, it is probably better find an exercise routine that is like and do it because you want to.

² There are several medical conditions that offer a small number of repeatable and accurately measured variables to be useful. Diabetes is an example. It will get better with better sampling and models, but current techniques are valuable and life-saving.

Also don't hold your breath for genetically-targeted nutrition recommendations - at least those with any science behind them.  Even if they did exist there is the problem of convincing people to adopt them.  

³ Brian Wansink of Cornell offers a number of useful psychology based mindless eating suggestions in his book by that title. 

 

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Recipe Corner

It is Winter and that means soup. I rarely use recipes, so here's a walkthrough of a lentil soup

Start off with a bag of lentils. All of them are different and all are good. Pick your favorite or just be random about it. Note the cooking time on the package and sort and rinse them. Add some olive oil to the bottom of a soup pot. I use a few glugs (how scientific) of an olive oil. You don't need a fancy $30 a bottle oil, but try to go with a real olive oil rather than a cheap mixed product. Turn the heat on low and start chopping the veggies. I generally start with a yellow onion, a couple of carrots, a stalk or two of celery, and a one or two smashed cloves of garlic (usually two:) Turn up the heat to medium and throw all of it in along with a pinch or two of sea salt. Stir as they get soft begin to smell good.

I usually add a few more veggies at this point. The last soup had fennel and the one before it had chopped acorn squash. Use your imagination. Toss them in and keep stirring.

Now add the spices. Decide on a direction. My last soup had a curry flavor from dried curry, cumin and turmeric. I pour some out onto my palm as a measure and dump them in. Just checking it worked out to about 1/2 tsp of each. For fun I added a bit of fresh lemon zest and stirred it all in. You don't want to heat them too much - just enough to toast them a bit - you'll know as they get very aromatic. Maybe a minute and a half to two minutes.

Add the lentils and a vegetable stock. I imagine chicken stock would work, but I'm vegetarian and don't go there. I make my own stocks and they're unsalted as it is too easy to over-salt a soup otherwise. I generally use a cup of lentils and four times as much stock. Feel free to vary if you like thicker or thinner soups.

Bring the soup to a boil and then cut the heat to a simmer uncovered. Go for softened lentils - don't let them get mushy. Also check any added veggies to make sure they're soft - a good reason for cutting them into small cubes.

Now add some chopped greens like spinach or swiss chard. They wilt in a minute or so and be bright green. Remove the pot from the heat when that happens. Now add a bit of lemon juice, sea salt to taste and serve. This is a good one for finishing with a fruity olive oil.

There are so many variations. Try it with some coconut milk for example... a bit of grated ginger.

These get better with practice and variation.