Which diet works for weight loss… low fat or low carb?

With all the diet books, videos, and podcasts available, it can be hard to determine what really IS the best way to eat healthy to lose weight.  So what REALLY works?  Does it matter if you eat low fat or low carb?

In the world of research, there are some that suggest your genotype (your genetic history) or insulin-glucose dynamics (how these levels change in your body over time) could impact which diet works better for you.  However, according to a clinical trial published in the Journal of the American Medical Association (JAMA), you can relax a little… there’s not a big difference statistically speaking.

For the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial, researchers wanted to more clearly define the effects of healthy low-fat (HLF) diet versus a healthy low-carbohydrate (HLC) diet on weight change.  They also wanted to pinpoint what, if any, impact genotype and/or insulin-glucose dynamics had on weight change.

Just over 600 adults aged 18-50 years were enrolled in the study in 2013, 2014 and early 2015.  All had a body mass index (BMI) of 28-40, but none were diagnosed with diabetes.  Study participants were randomly assigned to one of 2 groups, a 12-month HLF diet (305 participants) or a 12-month HLC diet (304 participants).  Additionally, they tested 3 genotype responsiveness patterns as well as insulin secretion to determine if they were linked to weight loss.

After preliminary testing and the randomization of the groups, participants attended 22 diet-specific health education sessions over 12 months.  The sessions focused on how to keep the lowest amount of fat/carbohydrate intake possible that could be maintained long-term.  The HLC group ate a diet that had a macronutrient distribution of 48 carb/29 fat/21 protein.  The HLF group ate a diet that had a macronutrient distribution of 30 carb/45 fat/23 protein.  The emphasis for both groups, was on high quality food selections.

At the conclusion of 12 months, each participant’s weight change was documented along with their diet group (HLC or HLF), genotype pattern, diet and insulin secretion.  Of the original 609 who began the study, 481 (79%) completed it.  Those in the HLF diet experienced a weight loss of -5.3kg (11.69 lbs).  Meanwhile the HLC lost 6kg (13.23 lbs).   They found no significant interaction between the diet and genotype interaction nor diet-insulin secretions.

Both groups saw improvement in lower blood pressure, insulin and glucose levels.  Due to the HLC group seeing an increase in low-density lipoprotein cholesterol concentrations (LDL), results favored the HLF group who experienced a significant increase in high-density lipoprotein cholesterol concentrations (HDL) and decrease in triglycerides among the HLC group.  Both groups saw a decrease in the prevalence of metabolic syndrome, but there was no significant difference between them.

What does this mean for you?

Obviously, there are many other variables that determine how a person’s body responds to a particular eating regimen.  Here are a few things to think about:

  • Any healthy eating routine will require planning. No eating plan will work if you don’t follow through with it.  Would one plan fit into your lifestyle more easily than another?  Take into account prep time, if fresh foods are readily available in your area, and if anyone in your home has specific dietary needs?  Constantly making separate meals to accommodate both diet needs would be difficult to maintain.
  • Do you have other health issues that can be addressed with diet? Some foods have been shown to have an impact on arthritis, eczema and other issues.  If you or your family have a history of high cholesterol, diabetes, or other diseases of this nature, your dietary habits can make a huge difference on if/when you develop those issues.   As this study shows, your diet can have a significant impact on your cholesterol levels.
  • What foods do you like? Again, no eating plan will work if you don’t stick with it.  Look at what healthy foods you enjoy and what new foods look the most appealing to you.  How can these be incorporated into new healthier eating habits?
  • Consider your options and talk to your doctor about factors that may help you determine which eating habits might be most beneficial to you. Then, once you begin, remember that you can always make changes if needed.

Common diet guidelines are great baselines, but each individual is different.  The most important thing is that your dietary habits are healthy overall.  Include a wide variety of foods, fresh produce and unprocessed (or minimally processed) foods in your meal plan as often as possible.

Your doctor of chiropractic can provide information about proper nutrition and activities to help your family live a happy and healthy lifestyle. As always, prevention is best, but if you have reached a point where you need to lose weight for health reasons, your chiropractor can help you devise a plan to lose weight and set realistic goals to keep you motivated and on track to better health.  Click here to find a doctor of chiropractic near you.


REFERENCE: Gardner CD, Trepanowski JF, Del Gobbo LC, et al.  “Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion The DIETFITS Randomized Clinical Trial.”  JAMA. 2018;319(7):667-679. doi:10.1001/jama.2018.0245.