Can Genetics Predict Which Diet is Best For You?

Written by Dr. Steve Chaney on . Posted in Genetics and Diet

Author: Dr. Stephen Chaney

 

genetix and dietIt is so confusing. The weight loss claims for popular diets sound so convincing, but they can’t all be true.

The low carb proponents give impressive metabolic arguments for why their diet works best. (Of course, you aren’t a biochemist. You have no idea whether they are speaking the truth or just trying to pull the wool over your eyes.) They quote clinical studies and offer testimonials that “prove” their diet works.

Other “experts” tell you that is nonsense. Your diet needs to be individualized to fit your genetic and metabolic profile. Who do you believe? Do low-carb or low-fat diets work better? Are individualized diet plans the solution?

Fortunately for you a recent study (CD Gardner et al, JAMA, 319: 667-679, 2018 ) has answered your questions. Let me start with some background to put this study in perspective. Then I will describe how the study was done, the study results, and what this study means for you.

 

What Did We Already Know About Diets?

The studies that low-carb proponents quote to “prove” the success of their diet approach are misleading because:

  • Most of the studies are short-term. This is misleading because low-carb diets lead to an initial loss of water weight that is not seen with low-fat diets.
  • Most of the comparisons are done with the typical American diet (which is high in sugar, refined carbohydrates, and junk food) rather than a healthy low-fat diet.
  • Note: This is the short version. I cover this in more detail in my new “Slaying The Food Myths” book.

In contrast, there have been numerous studies comparing the effectiveness of low-carb versus low-fat diets long term (12 months or more). These studies have not found a dimes worth of difference between the two diets. Weight loss was virtually identical.

genetix and diet bestThat has led some weight loss experts to point out that any “one size fits all” diet fails to account for individual variability. They point out that while average weight loss on a particular diet might be 12-15 pounds, some people will have lost 45 pounds and others gained 5 pounds. That has led to research efforts to discover biomarkers that could predict which diet will work best for you. Let me share the two most promising approaches.

A DNA testing approach measures genetic variation in the PPARG, ADRB2, AND FABP2 genes [Don’t worry. There won’t be a quiz.] These are genes involved in fat and energy metabolism. Animal studies have suggested that genetic variation in these genes might be useful in predicting whether individuals respond better to a low-fat or low-carb diet. One preliminary clinical study has suggested it may work for humans as well.

An insulin sensitivity approach measures insulin levels 30 minutes after a glucose challenge (a measurement called INS-30). Some small clinical studies have suggested this approach might also have value in predicting the success of low-carb versus low-fat diets for weight loss.

Unfortunately, some companies are already promoting individualized diet plans based on DNA testing and insulin sensitivity measurement – even though the clinical support for the predictive power of those tests is very preliminary at present.

The current study was designed to compare the effectiveness of healthy low-carb and low-fat diets on weight loss. In addition, it evaluated whether either DNA testing or insulin sensitivity measurements could effectively predict whether individuals lost weight better on low-fat or low-carb diets.

How Was This Study Done? 

genetix and diet studyThis was an excellent study. In fact, it is one of the best studies comparing weight loss diets I have seen in recent years. It enrolled 609 middle-aged (average age = 40), overweight (average BMI = 33) adults from the San Francisco Bay area in a 12-month weight loss study. Here was the breakdown of participants:

  • 57% were women, 43% were men.
  • 40% had a DNA pattern considered favorable for a low-fat diet, 30% had a DNA pattern considered favorable for a low-carb diet (30% had an intermediate DNA pattern that did not predict either low-carb or low-fat).
  • 67% had insulin sensitivity values considered favorable for low-carb diets, 33% had insulin sensitivity considered favorable for a low-fat diet.

The study participants were randomly assigned to either the low-carb diet group or low-fat diet group by a computerized protocol that assured DNA patterns and insulin sensitivity were equally distributed across the two groups.

In contrast to many earlier studies, both groups followed a relatively healthy diet. They were instructed to:

  • Maximize vegetable intake.
  • Minimize intake of added sugars, refined flours, and trans-fats.
  • Focus on whole foods that were minimally processed, nutrient dense, and prepared at home whenever possible.

The participants were not advised to restrict their calories. However, they were given an extraordinary degree of support. They were further divided into groups of 17 that met a total of 22 times over the 12 months with a registered dietitian who provided instruction, support and encouragement. That level of support assured that the participants stuck with their diet for the full 12-month period.

 

Can Genetics Predict Which Diet Works Best?

genetix and diet works best Participants in the study lost an average of 12 pounds. That is not a huge amount of weight, but it is enough weight loss to make a difference, and it is consistent with the results of most long-term studies. When the results were broken down further:

  • There was no significant difference in weight loss between the low-carb group and low-fat group at 12 months. This is consistent with multiple previous studies.
  • Both diets were equally effective at improving lipid profiles and lowering blood pressure, insulin, and blood sugar levels. This is the dirty little secret that many low-carb enthusiasts don’t tell you. The improvements seen in health parameters such as lipids, blood pressure, insulin, and blood glucose are due to the weight loss, not whether the diet is low-carb or low-fat.
  • Neither the DNA pattern or insulin sensitivity offered any predictive value as to whether a low-carb or low-fat diet was more effective for weight loss.

That does not mean that DNA testing is of no value. It simply means that the human genome is far more complex than the companies offering DNA tests have assumed. There will be a day when we know enough to individualize diets based on DNA testing. That day is not now.

What Does This Mean For You?

Forget the weight loss claims of the low-carb enthusiasts. Ignore companies that promise they can select the best diet approach for you based on some simple DNA tests and/or measurements of insulin sensitivity.

This study does not provide definitive answers, but it hints at the weight loss tips that really matter:

  • Ditch the sodas, sweets, fast and processed foods. Instead focus on whole foods, primarily fruits and vegetables, whole grains, and legumes.
  • If you wish to follow a low-carb diet, choose one that is primarily plant-based  rather than meat-based.
  • Focus on what you are eating rather than on calories.
  • Find a group to provide support and encouragement. It doesn’t need to be some expensive diet program. It could just be a group of friends who agree to provide each other with support, encouragement, and accountability.

I cover this topic in much more detail in my new book “Slaying The Food Myths”.

 

The Bottom Line:

 

A recent study compared the effectiveness of healthy low-carb and low-fat diets on weight loss over a 12-month period. In addition, it evaluated whether DNA testing or insulin sensitivity measurements could effectively predict whether individuals lost weight better on low-fat or low-carb diets.

  • There was no significant difference in weight loss between the low-carb and low-fat groups at 12 months. This is consistent with multiple previous studies.
  • Both diets were equally effective at improving lipid profiles and lowering blood pressure, insulin, and blood sugar levels. This is the dirty little secret that many low-carb enthusiasts don’t tell you. The improvements seen in health parameters such as lipids, blood pressure, insulin, and blood glucose are due to the weight loss, not whether the diet is low-carb or low-fat.
  • Neither the DNA pattern or insulin sensitivity offered any predictive value as to whether a low-carb or low-fat diet was more effective for weight loss.

That means you can forget the weight loss claims of the low-carb enthusiasts. You should also ignore companies that promise they can select the best diet approach for you based on some simple DNA tests and/or measurements of insulin sensitivity.

As for what works and why, I cover that in detail in my new book “Slaying The Food Myths

 

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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Latest Article

How to Choose the Right Pillow

Posted April 17, 2018 by Dr. Steve Chaney

Wake Up Each Morning Pain Free

Author: Julie Donnelly, LMT – The Pain Relief Expert

Editor: Dr. Steve Chaney

 

how to choose the right pillow without headachesThe way you sleep is often a key to discovering the cause of headaches and more. If you wake up with neck pain, a headache, or you suffer from ringing in your ears, dizziness, or ear pain, there is a good possibility that it may be caused by the way you are sleeping. Your pillow may be the culprit.  But if you need to know how to choose the right pillow for you, it’s easy.   It just takes a little “investigation.”

 

How to Choose the Right Pillow if You Sleep On Your Side

Your head, neck, and spine need to always stay in a nice straight line, just as it is when you are standing up, but that takes a little thought and understanding of the way you sleep.  So, get comfy in your bed and then notice how your head is resting.

how to choose the right pillow to sleep painfreeIf you sleep on your side, your pillow needs to be just the right size, so your head doesn’t point down toward the mattress (your pillow is too soft) or up to the ceiling (your pillow is too thick). Either of these positions will make the muscles on the side of your neck stay in the contracted position for hours and pull your vertebrae in that direction, especially when you try to turn over to your other side.

Your SCM Muscle May Cause Serious Problems

You also need to notice if you turn your head a bit, especially if you are turning into your pillow or turning your head up toward away from your pillow. In either of these two cases you will be causing your sternocleidomastoid (SCM for short) to be held shortened for hours.

Your SCM originates on your collarbone and inserts into the bone behind your ear.  When it contracts you turn your head to the opposite side. However, if the muscle is tight (for example, when you’ve held your head turned toward one side for an extended period of time) and then you bring your head back so you are facing forward, the tight muscle will pull on the bone behind your ear and cause havoc.

The symptoms for a tight SCM are tinnitus (ringing in the ear), dizziness, loss of equilibrium, ear pain, headaches, pain in the eye and around the skull, pain at the top of the head, and even pain in the throat. Amazing! What’s even more amazing is that it’s rare that this muscle is considered when a medical professional is searching for the cause of your symptoms.

These are the things to know when considering how to choose the right pillow if you sleep on your side.

How To Choose The Right Pillow If You Sleep On Your Back

how to choose the right pillow for sleeping on your backIf you sleep on your back, your head should be on the mattress (not propped up with a pillow) and you should have a tiny support (like a folded washcloth) under your neck.  Or, you can have a wedge pillow that starts at your mid-back and gently raises your entire trunk and head up while still allowing your head and back to be in a straight line.

It’s always a challenge for people who toss and turn during the night, sometimes on their side and sometimes on their back.  The best thing I’ve found for this situation is to have the pillow below shoulder level so when you turn on your side your shoulder will automatically slide to the edge of the pillow while still supporting your head properly, and when you turn onto your back, the pillow will start at shoulder level so your head and neck are supported, but your head is being pushed in a way that causes your chin to move down to your chest.

hip pain causes and treatment pain freeIt’s tricky, but I can personally attest to the fact that it will work.  I can always tell when I’ve had my head tilted (I toss and turn during the night) because I will wake with a headache. When that happens I’m grateful that I know how to self-treat the muscles of my neck and shoulders so the headache is eliminated quickly.  If you already have Treat Yourself to Pain Free Living,  you can self-treat all your neck and shoulder muscles to release the tension.

How To Choose The Right Pillow If You Sleep On Your Stomach

If you sleep on your stomach, this is the one position that is so bad that it behooves you to force yourself to change your position. Your head is turned to the side and held still for hours, putting a severe strain on all your cervical and upper thoracic vertebrae. Not only will this cause headaches, tinnitus, and a list of other pains, but it can cause problems down your entire spine. It can also impinge on the nerves that pass through the vertebrae on their way to your organs.

If you do sleep that way, let me know and I’ll give you some suggestions that work to change your habit of sleeping. It takes time and energy, but the results are worth the effort.

In every case, the way you sleep may cause neck pain that won’t go away until the pillow situation is resolved.

Now you should know how to choose the right pillow for the way you sleep.

Wishing you well,

Julie Donnelly

About The Author

julie donnelly

Julie Donnelly is a Deep Muscle Massage Therapist with 20 years of experience specializing in the treatment of chronic joint pain and sports injuries. She has worked extensively with elite athletes and patients who have been unsuccessful at finding relief through the more conventional therapies.

She has been widely published, both on – and off – line, in magazines, newsletters, and newspapers around the country. She is also often chosen to speak at national conventions, medical schools, and health facilities nationwide.

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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