Does Genetics Determine Weight?

Written by Dr. Steve Chaney on . Posted in Health Current Events, Healthy Lifestyle, Obesity

Does Genetics Cause Obesity?

Author: Dr. Stephen Chaney

Overweight & Skinny WomenIt’s frustrating. Try as hard as you might, you just can’t seem to lose weight. Even worse you suspect that your friends – and maybe your doctor – assume that you are cheating on your diet. It just doesn’t seem fair.

Perhaps there is a simple explanation. Maybe your genes are keeping you from losing weight. Does genetics determine weight?  It has been hypothesized that some of us have a “thrifty” phenotype when it comes to weight loss while others are “spendthrifts”. The theory is that people with a “thrifty” phenotype hold on to weight more tightly when they are “fasting” (i.e. trying to lose weight) and gain weight more readily when they are “feasting” (i.e. eating excess calories).

The metabolism of the “spendthrifts” is exactly the opposite. They lose weight rapidly when fasting and gain weight slowly when feasting. Those would be all of your skinny friends who just can’t seem to understand why you have such difficulty losing weight.

Those experts who favor the “thrifty” phenotype hypothesis point out that it would have provided a tremendous survival advantage in prehistoric times when food was scarce. That’s why some of those same experts think that up to 80% of the population has the “thrifty” phenotype. When you couple the thrifty phenotype with the typical American diet and lifestyle it becomes easy to understand why we have an obesity epidemic in this country.

Is the “thrifty” phenotype hypothesis true? Could it explain why you have such difficulty losing weight? A recent study suggests the answer to those two questions may be yes. I will outline the evidence below.

Then I will address what are probably the two most important questions for you: “If the thrifty phenotype hypothesis is true and you have the thrifty phenotype, are you destined to be overweight? Is there anything you can do about it?

How The Study Was Designed

medical studyThis study (Reinhardt et al, Diabetes, 64: 2859-2867, 2015) was truly a remarkable study. 15 healthy, but obese volunteers were put in a metabolic ward for a total of 11 weeks. In the metabolic ward every aspect of their metabolism was closely controlled and measured.

  • They were given diets that were precisely calibrated to provide a predetermined caloric (energy) input.
  • Urine and feces were collected and analyzed in an instrument called a bomb calorimeter to determine calorie (energy) output.
  • They were limited to primarily sedentary activity for the duration of the experiments, and the temperature of the metabolic ward was maintained constant. This eliminated variation in energy expenditures due to activity and temperature.
  • Metabolic energy expenditure was calculated by placing them in a special room designed to precisely measure oxygen consumption and CO2 production by the subjects over a 24 hour period. Don’t worry about the details. Just know that this is the gold standard for measuring energy expenditure.

Here is what the subject’s 11 weeks in the metabolic ward looked like:

  • During the first 3 weeks the subjects were provided with a diet designed with just enough calories to maintain their weight based on their weight and sex. If weight gain or loss was observed the calories were adjusted accordingly.
  • During one 24 hour period in week 3 the subjects were place on a diet that decreased their calories by 50%, (defined as “fasting” in this study) and the resulting decrease in metabolic energy expenditure was measured as described above.
  • During another 24 hour period in week 3 the subjects were place on a diet that increased their calories by 200% (defined as “overfeeding” in this study), and the resulting increase in metabolic energy expenditure was measured.
  • During the next 6 weeks the subjects were placed on calorie restricted diet that only provided 50% of the calories they needed to lose weight.
  • During the final 2 weeks the subjects were placed on a diet designed to provide the calories needed to maintain their new weight, whatever it was.

How Does Genetics Determine Weight?

do genetics cause obesityThe results of the study were quite interesting:

  • All of the subjects lost weight, but the amount of weight loss ranged from 5% to 12% of the original body weight.
  • Their starting weight did not influence their rate of weight loss during calorie restriction, but their metabolic response to fasting and overfeeding significantly affected their rate of weight loss. Specifically:
  • The subjects with the smallest decrease in energy expenditure during fasting and the largest increase in energy expenditure during overfeeding (the spendthrifts) lost significantly more weight during the 6 week caloric restriction period (what most of us call a diet).
  • The subjects with the largest decrease in energy expenditure during fasting and the smallest increase in energy expenditure during overfeeding (the thrifty) lost significantly less weight during the 6 week caloric restriction period.
  • The amount of caloric restriction needed to lose one pound of weight ranged from 1,558-2,993 depending on whether the subjects displayed the spendthrift or thrifty phenotype. That’s almost a 2-fold difference.

What Does This Study Mean For You?

life-is-sometimes-unfairLife isn’t fair. You probably already suspected that. Your skinny friends actually do have a much easier time losing weight than you do. In fact, they may be able to lose up to twice the amount of weight with exactly the same amount of caloric restriction.

However, the good news is that weight loss is possible – even for you. Everyone in the study lost weight – even those subjects with the thriftiest phenotype. So the question becomes what can you do to lose weight successfully? Here are 5 simple tips.

#1: Don’t give up. Stick with it. Pounds may come off slowly for you, but this study shows they will come off. You just have to keep the faith and be consistent.

#2: Watch what you eat very carefully. The researchers in this study controlled every morsel of food the subjects ate. People always lose weight more rapidly when they are in a metabolic ward. My recommendation is to track what you eat daily using one of the many available tracking apps.

#3: Be consistent with your exercise. The subjects in this study were not allowed to exercise, but that is one of the best ways to increase energy expenditure. Aerobic exercise gives you a small increase in energy expenditure during and immediately following the exercise. Weight bearing exercise gives a long term increase in energy expenditure because it increases muscle mass, and muscle burns calories faster than any other tissue.

#4: Choose a diet that preserves muscle mass (High Protein Diets and Weight Loss ) while you are losing weight.

#5: Avoid all those diets with herbal and pharmaceutical stimulants. They are dangerous and they may just kill you.  Check out  Are Dietary Supplements Safe.

 

The Bottom Line

A recent study (Reinhardt et al, Diabetes, 64: 2859-2867, 2015) did a very careful metabolic analysis and divided subjects into what they characterized as either a “thrifty” or “spendthrift” phenotype based on their changes in metabolic energy expenditure in response to fasting and overfeeding. They then looked at how those phenotypes affected weight loss during a 6 week period of caloric restriction. Does genetics cause obesity or help determine weight?  Here’s what they found:

  • All of the subjects lost weight, but the amount of weight loss ranged from 5% to 12% of the original body weight.
  • Their starting weight did not influence their rate of weight loss during caloric restriction, but their metabolic response to fasting and overfeeding significantly affected their rate of weight loss. Specifically:
  • The subjects with the smallest decrease in energy expenditure during fasting and the largest increase in energy expenditure during overfeeding (the spendthrifts) lost significantly more weight during the 6 week caloric restriction period (what most of us call a diet).
  • The subjects with the largest decrease in energy expenditure during fasting and the smallest increase in energy expenditure during overfeeding (the thrifty) lost significantly less weight during the 6 week caloric restriction period.
  • If you struggle to lose weight, this is a good news – bad news study.
  • The bad news is that life isn’t fair. You probably already suspected that. Your skinny friends actually do have a much easier time losing weight than you do.
  • The good news is that weight loss is possible – even for you. Everyone in the study lost weight – even those subjects with the thriftiest phenotype. So the question becomes what can you do to lose weight successfully? I’ve given you 5 simple tips in the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Should You Avoid Sugar Completely?

Posted October 24, 2017 by Dr. Steve Chaney

Is It The Sugar, Or Is It The Food?

Author: Dr. Stephen Chaney

 

Should we avoid sugar completely?  Almost every expert agrees that Americans should cut down on the amount of sugar we are consuming. However, for some people this has become a “sugar phobia”. They have sworn that “sugar shall never touch their lips”. Not only do they avoid sugar sweetened sodas and junk food, but they also have become avid label readers. They scour the label of every food they see and reject foods they find any form of sugar listed as an ingredient. Is this degree of sugar avoidance justified?

 

Should We Avoid Sugar to Keep it From Killing Us?

 

Let me add some perspective:

  • If you just take studies about the dangers of sugar at face value, sugar does, indeed, look dangerous. Excess sugar consumption is associated with increased risk of obesity, diabetes, and heart disease. However, when you look a little closer, you find that most of these studies have been done by looking at the correlation of each of these conditions with sugar sweetened beverage consumption (sodas and fruit juices).

A few studies have looked at the correlation of obesity and disease with total “added sugar” consumption. However, 71.6% of added sugar in the American diet comes from sugar sweetened beverages and junk food. None of the studies have looked at the sugar from healthy foods like fruits, vegetables, and whole grains. That’s because there is ample evidence that these foods decrease the risk of obesity, diabetes, and heart disease.

  • For example, if apples had a nutrition label, it would list 16 grams of sugar in a medium 80 calorie apple, which corresponds to about 80% of the calories in that apple. The sugar in an apple is about the same proportion of fructose and glucose found in high fructose corn syrup. Apples are not unique. The nutrition label would read about the same on most other fruits. Does that mean you should avoid sugar from all fruits? I think not.

Avoid Sugar or Avoid Certain Foods

 

avoid sugar from junk foodsThe obvious question is: “Why are the same sugars, in about the same amounts, unhealthy in sodas and healthy in fruits?” Let’s go back to those studies I just mentioned—the ones that are often used to vilify sugars. They are all association studies, the association of sugar intake with obesity and various diseases.

The weakness of association studies is the association could be with something else that is tightly correlated with the variable (sugar intake) that you are measuring. Could it be the food that is the problem, not the sugar?

If we look at healthy foods (fruits, vegetables, whole grains) they are chock full of vitamins, minerals, phytonutrients, fiber, and (sometimes) protein. Fiber and protein slow the absorption of sugar into the bloodstream. As a result, blood sugar levels rise slowly and are sustained at relatively low levels for a substantial period of time.

In sodas there is nothing to slow the absorption of blood sugar. You get rapid rise in blood sugar followed by an equally rapid fall. The same is true of junk foods consisting primarily of sugar, refined flour and/or fat.  Avoid sugar from those types of foods.

Another consideration is something called caloric density. Here is a simple analogy. I used to explain the concept of caloric density to medical students in my teaching days. There are about the same number of calories in a 2-ounce candy bar and a pound of apples (around 278 in the 2-ounce candy bar and 237 in a pound of apples). You can eat a 2-ounce candy bar and still be hungry. If you eat a pound of apples you are done for a while. In this example, the 2-ounce candy bar had a high caloric density (a lot of calories in a small package). Perhaps a more familiar terminology would be the candy bar was just empty calories.

Are Sodas and Junk Foods Killing Us?

avoid sugar from candyPutting all that together, you can start to understand why the foods the sugars are in are more important than the sugars themselves. When you consume sugars in the form of sugar sweetened beverages or sugary junk foods, your appetite increases. We don’t know for sure whether it is the intense sweetness of those foods, the rapid increase and fall in blood sugar, or the high caloric density (lots of calories ina small package) that makes us hungrier. It doesn’t matter. We crave more food, and it isn’t usually fruits, vegetables, and complex carbohydrates we crave. It’s more junk. That sets in motion a predictable sequence of events.

  • We overeat. Those excess calories are stored as fat and we become obese. [Note: The low carb enthusiasts will tell you our fat stores come from carbohydrates alone. That is incorrect. All excess calories, whether from protein, fat, or carbohydrate, are stored as fat.]
  • It’s not just the fat you can see (belly fat) that is the problem. Some of that fat builds up in our liver and muscles. This sets up an unfortunate sequence of metabolic events.
  • The fat stores release inflammatory cytokines into our bloodstream. That causes inflammation. Inflammation increases the risk of many diseases including heart disease and cancer.
  • The fat stores also cause our cells to become resistant to insulin. That reduces the ability of our cells to take up glucose, which leads to hyperglycemia and type 2 diabetes. [Note: The low carb enthusiasts will tell you carbohydrates cause type 2 diabetes. That is also incorrect. It is our fat stores that cause insulin resistance and type 2 diabetes. Our fat stores come from all excess calories, not just excess calories from carbohydrates.]
  • Insulin resistance also causes the liver to overproduce cholesterol and triglycerides and pump them into the bloodstream. That increases the risk of heart disease.
  • Sugar sweetened beverages and sugary junk foods also displace healthier foods from our diet. That leads to potential nutrient shortfalls that can increase our risk of many diseases.

However, none of this has to happen. The one thing that every successful diet has in common is the elimination of sodas, junk foods, fast foods and convenience foods. You should avoid sugar from those foods as much as possible. Once you eliminate those from your diet,you significantly enhance your chances of being at a healthy weight and being healthy long term.

 

What About Protein Supplements And Similar Foods?

Of course, the dilemma is what you, as an intrepid label reader, should do about protein supplements, meal replacement bars, or snack bars. They are supposed to be healthy, but the label lists one or more sugars. Even worse, the sugar content is higher than your favorite health guru recommends.  So, should you avoid sugar from supplements and the like?

In this case, a more useful concept is glycemic index, which is a measure of the effect of the food on your blood sugar levels. Healthy foods like apples may have a high sugar content, but they havea low glycemic index.

avoid sugar and consume protein to slow absorbptionThe same is true for the protein supplements and bars you are considering. Rather than looking at the sugar content, you should be looking for the term “low glycemic” on the label. That means there is enough fiber and protein in the food to slow the absorption of sugar into the bloodstream and stabilize your blood sugar levels.

What Does This Mean For You?

Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should work on ways to avoid sugar or reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners. I have warned about the dangers of artificial sweeteners previously.

We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. For example, some Starbucks drinks are mostly sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

So we don’t have to avoid sugar completely, but we should reduce sugar from sugar sweetened beverages and junk food.

 

The Bottom Line

 

We need to keep warnings about the dangers of sugar in perspective:

  • The studies showing that sugar consumption leads to obesity, diabetes, and heart disease have all been done with sodas and junk foods.
  • Many fruits have just as much sugar as a soda. They also contain about the same proportion of fructose and glucose as high fructose corn syrup. Yet we know fruits are good for us.
  • Diets rich in fruits, vegetables and whole grains decrease our risk of obesity, diabetes, and heart disease.
  • That is because the sugar in whole foods is generally present along with fiber and protein, which slows the absorption of sugar and prevents the blood sugar spikes we get with sodas and junk foods.
  • In the case of prepared foods like protein supplements, you should look for “low glycemic” on the label rather than sugar content. Low glycemic means that there is enough fiber and protein in the product to slow the absorption of sugar and prevent blood sugar spikes.
  • Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should all work on ways to avoid sugar from junk foods or to reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners.
  • We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

For more details, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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