21 August 2008
First, thanks to MizFit for featuring my thoughts in her valuable space. And thanks to all people for whom that writing resonates and have come here as a result.
The following links are to some of my best and/or most popular posts.
Introductory Post - I Are Engineer
Diet Post - Unified Feed Theory
Diet Post - Healthful Eating
Relationships - Emotional Needs In A Relationship
Relationships - The Nature of Love Part 1, Falling In Love
Relationships - The Nature of Love Part 2, Staying In Love
Relationships - In Praise of Joy Toys
Communication - Communication 101
Communication - Communication 201
Communication - Active Listening and Feedback
General Framework - Does Free Will Exist?
General Framework - Feeling are Facts
Miscellaneous - The Importance of Vacations
Please make yourself at home here, sign up for updates and feel free to leave comments.
15 August 2008
Disclaimer: The following text is at the end of this as well.
Obesity is a charged word. Some people hear it and think bad things about someone. Others hear it and get angry because we as a society are not "fat-accepting." Whatever your weight is, you are beautiful. You are you. Accept yourself for what you are today. You may wish to make physical changes, but first, love yourself.
A recent article that appeared in newspapers and magazines throughout the country had the following headlines: "Fit and fat: US study shows it's possible." and "Study: Fat people not necessarily heart risks." The real headline should have been "Study shows strongly positive correlation between large weight to height ratio and symptoms of metabolic syndrome." Of course since excess fat accumulation is also a symptom of metabolic syndrome, this would not have been a surprise to anyone.
From the headlines you would think that the article will say that obesity is OK, and the article kind of does say that. It emphasizes that not all people defined as obese have metabolic problems and many people defined as "normal weight" have metabolic problems.
This table shows what the study actually describes. Obese people have a much higher probability of cardiometabolic abnormalities than lighter weight people. Even if you are light weight, you still have a chance of cardiometabolic problems. The articles do not discuss causality or mitigation techniques, just correlations and associations. The New York Times article was more even-handed than most.
If you read nothing else in this post, I hope you understand how misleading the reporting is on the story.
The articles do not tell the whole tale
There are some interesting potential issues not brought up in the articles. The first is the definition of obesity. Typically, researchers apply the obese label to anybody with more than 30 BMI.
On the other send of the spectrum are the skinny fat people. They have a low BMI, but they work really hard with cardio and diet. They have probably had weight problems in the past and have experienced some yo-yo dieting. Their arms and legs are skinny, but maybe they have a bit of a gut. These people can easily have body fat percentage greater than 25%, yet they count in here as skinny. I would estimate that there are more people in this category than fit people in the obese category. There are probably lots of both in the overweight category.
A better metric mitght be the FMI or Fat Mass Index. It is very similar to BMI and is in fact a component of it.
Remember BMI is
It can be broken down to
= [ lean weight in lbs / (height in inches)^2 + fat weight / (height in inches)^2 ] * 703
Removing the lean weight part, we are left with the Fat Mass Index (FMI or BFMI)
FMI = [ fat weight / (height in inches)^2 ] * 703
Removing the fat weight from the BMI equation gives the Fat Free Mass Index (FFMI)
FFMI = [ (lean weight in lbs / (height in inches)^2 ] * 703
Adjusted FFMI = [ (lean weight in lbs / (height in inches)^2 ] * 703 + 6.0 * ( Height (m) - 1.8 )
According to this link (which also has an FFMI calculator), an upper limit FFMI for a steroid-free person is about 25. This abstract addresses the variations in FMI and FFMI associatedf with given BMIs. Here's another one.
Second, there were no indicators of age in the articles. What factor would age play in cardiovascular and metabolic risk. Does it matter how long a person has been overfat? Wouldn't a person become more insulin resistant over time. How many of the healthy overweight and obese people in the study were still young and have not had time to build up insulin resistance?
Finally, the measures used were blood pressure, cholesterol, triglycerides, and blood sugar. It did not measure actual mortality, only factors that correlate with problems. We don't know if heavier people would have lower mortality from other causes.
So I believe we should define obese in terms of body fat, not BMI. It's a continuum really and different people carry fat differently and our measurement techniques for body fat are inaccurate, so I will define obesity as follows: If you are a male and have more than 20% body fat or a female and have more than 25% body fat you probably have some health issues causing fat accumulation.
If you don't have access to a reliable body fat measuring device, consider the following. If you have a BMI over 30 and think that maybe you are not actually obese, one way to measure it is through strength. If you are a male, drop and do 25 high quality push-ups. if you can't pretty easily, you probably have too much fat.
So What? Is fat bad?
I'm not sure really. Excess fat is often a symptom of some underlying physical problems, although it may not be bad in and of itself.
Limits options: One of the ten emotional needs in a marriage according to Stephen Harley is physical attractiveness. If you are not physically attractive to someone due to obesity, the chemistry so important in the early stages of a relationship may not be there. Likewise, if you have become overfat since the start of the relationship, you may not be able to provide that emotional need for your partner. By all means try to change our societal view of beauty, but the current reality is what it is,
This blogger has an interesting perspective. Her viewpoint is that obesity is a fact and part of our culture. We should learn how to medically treat people with obesity rather than simply blaming their problems on the obesity.
Obesity is a charged word. Some people hear it and think bad things about someone. Others hear it and get angry because we as a society are not "fat-accepting." Whatever your weight is, you are beautiful. You are you. Accept yourself for what you are today. You may wish to make changes, but first, love yourself.
The following link is a tool that can assist you in measuring your body fat percentage. It's cheaper than a Tanita scale and can give you another perspective on your health.
08 August 2008
Many people believe that exercise is a great way to lose weight and keep trim. This fits in with our societal beliefs that obesity is caused by eating to much and not exercising enough, or as Taubes calls it, "gluttony and sloth." That is generally not true, and research backs it up. This recent study conducted by the University of Pittsburgh shows little difference between the exercise groups on a low fat diet ('Weight loss did not differ among the randomized groups at 6 months' (8%-10% of initial body weight) or 24 months' (5% of initial body weight) follow-up.") and the initial weight loss comes back on the same trajectory regardless of amount of exercise. Their conclusion was that 275 mins per week of vigorous exercise in addition to calorie reduction is "important in allowing overweight women to sustain a weight loss of more than 10%." They didn't mention that the women who actually ended up 10% lower weight were also restricting their Calories more than the others. This is a typical case of cognitive dissonance, seen in research all the time.
Here is a pretty good analysis of the study. She has access to the paper and data that I don't. Be careful though. She also says that long term weight loss doesn't happen at all, because of the "setpoint." She's wrong about that. Here's an analysis of another study that shows that physical activity correlates with higher weight. It doesn't address the composition of the weight however (fat vs. muscle).
This is a discussion of another study that shows that society has increased its level of activity, even while obesity rates have been increasing. It puts another nail in the coffin of sloth.
So why doesn't exercise work for fat or weight loss? There are a few ways to look at it. First, and most simply, burning significant calories through exercise takes lots of time and work. An hour of heavy aerobic work by a medium sized person might burn 600 Calories or so above your basal metabolic rate. One hamburger undoes all that.
The other more basic issue is that when you burn those calories through exercise, you are using the fuel in your body. Your cells still need fuel and to the extent you exceed the fat burning capacity of your system, you will feel hunger. Fundamentally, exercise does not blunt hunger like a proper diet can, so it becomes much less automatic and prone to failure. Some people ramp up the exercise and "willpower" their way into additional weight loss, but if you exceed the capacity of your body to burn its own fat, the weight loss will come from muscle instead of fat, and your metabolism will slow down because it senses starvation.
A Thought Experiment - Some Weight Loss Scenarios
You have a guy. He's in ok cardiovascular shape, carrying a little extra fat. Let's say he's are 6' tall, 200 lbs and 20% body fat. His daily energy need is 2,500 Calories. He decides to lose weight. What will be the outcome of the different approaches?
Note: In physics class you learned that a calorie is the amount of heat needed to change the temperature of 1 ml of water by 1 degree centigrade. In nutrition, a Calorie is actually a kilo-calorie (kcal). I have generally tried to follow the convention that capital-C Calorie is a kcal.
Cut carbs, get plenty of protein, restrict calories to 1500 calories per day.
Eat normal, standard American diet (65% carbs, 20% protein, 15% fat), exercise 600 calories beyond BMR per day.
Intense Exercise and Diet Approach
Cut back on calories as in the diet-only approach. Do lots of aerobics and resistance training (600 calories per day) to enhance the calorie deficit.
The subject will have a caloric deficit of about 1,000 Calories per day. This will result in a weight loss equivalent of 7,000 Calories or 2 lbs of fat per week. He is carrying about 40 pounds of fat initially, so he will be able to burn a maximum of 1,240 Calories of fat from his body per day. Assuming his low-carbohydrate approach minimizes insulin response, the majority of the calories should be from fat. As he loses weight his ability to burn fat reduces, so he will have to run less of a deficit. Once his body adapts to fat burning, he will likely not feel terribly hungry most of the time.
The subject will have a caloric deficit of about 600 Calories per day. This will result in a weight loss equivalent of 4,200 Calories or 1.2 lbs of fat per week. He is carrying about 40 pounds of fat initially, so he can support up to 1,240 Calories of fat from his body per day. One troubling aspect of this approach is that the realtively high carbohydrate content of his diet will likely induce an insulin response and thus inhibit fat-burning. Even though the net calorie restriction is less than the diet-only approach, the subject will feel hungry more and will have to "willpower" his way through to losing weight. With this type of approach, weight gain is highly likely if his routine is interrupted.
Exercise and Diet Approach
The subject will have a caloric deficit of about 1,600 Calories per day. This will result in a weight loss of 10,200 calories per week, or almost 3 lbs of fat. There is a potential pitfall here though. He will be exceeding his body's ability to use its own fat stores by about 360 Calories per day. His low-carb approach will allow for use of his fat as fuel, but once that reaches its limit, he will cannibalize muscle for fuel. This will cause hunger, and likely big drops in his metabolic rate. He will have a lack of energy and his physical capacity will decline.
What Does This Tell Us?
The bottom line is that fat-loss is limited by the body's ability to use internal fat as fuel. Fat loss can occur through either exercise or diet. Just don't push it too hard. Resistance exercise will help maintain muscle strength and also signal your body to send protein to the muscles that have been worked. If the combination of what you eat, plus what you burn from your fat stores is equal to or greater than your caloric needs your muscle loss (or catabolism) will be minimized.
On a low carbohydrate diet, your ability to replenish fuel for your muscles will likely be inhibited in the case of high-intensity or longer medium intensity exercise, so you may wish to increase carbs somewhat for those purposes. I think of it as "buying carbs" with high-intensity exercise. If you don't get sufficient carbs before high-intensity exercise you may bonk (run out of muscle fuel). Here's another interesting perspective on the bonk. With low intensity exercise (walking or light aerobics), you should be able to use fat for the majority of your energy needs.
This link will allow you to look at your own numbers. you will need to export the spreadsheet to your own computer.
But Lots of People Use Aerobics to Keep Trim
We all know people who eat whatever they want, then maintain a super-active lifestyle and so never put on any weight. So those people can argue that exercise is what keeps them thin. But the method contains the seeds of failure. Eventually, most people will get injured or sick. When that happen, people with poor diets and lots of activity will tend to put weight on rapidly. They are swimming upstream with their approach to weight loss and maintenance. You can make progress, but if they stop paddling for a second, they lose everything and then some.
Net calories matter, but it's only part of the story for weight loss. Spark of Reason blog has a great write-up on conservation of energy.
To lose or maintain weight, get your diet right first as spelled out in my previous posts here, here, and here. Do exercise to build and maintain muscle and fitness. If you are going to make one change in your life to affect your weight and fitness, fix your diet first.
Why Exercise Then?
Exercise carries many benefits not related to weight loss. Regardless of the weight issue, exercise has a number of benefits including: physical appearance, maintenance of muscle, confidence/self esteem, ability to be active, improved blood pressure, plus chemical advantages, such as increased High Density Lipoproteins (HDLs). I will cover that in future posts.
Addendum 8/15/08: Exercise, especially resistance exercise, might cause weight to increase (by increasing muscle mass). It's good weight though. Even though your BMI may go up, you will also be decreasing your percent body fat.