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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Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

For more details on the study, 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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