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Research Review: Insulin Sensitivity Determines Weight Loss Success, Adherence and Dieting Flexibility

Adherence to a Low-Fat versus Low-Carbohydrate Diet Differs by Insulin Resistance Status

McClain et al. 2013

    • Insulin resistance is associated with high BMI, weight, and body fat levels.
    • Insulin resistant individuals were less likely to adhere to a low-fat diet.
    • Both insulin sensitive and insulin resistant individuals had the greatest success in weight loss and adherence to a low carbohydrate diet.
    • Insulin sensitive individuals showed high adherence and weight loss success on both low fat and low carb diets.
    • People with high BMI, weight, and body fat percentages may be wise to start off with a low carb diet for the best weight loss success, based on this study.


This study examined the relationship between insulin-resistance status, e.g. your ability to utilize and digest carbohydrates.

They assessed insulin resistance in individuals and how this correlated to dietary adherence when on either a low fat (<10% fat) or low carb (<50g carbs/day) diet.

This study found that insulin resistant participants (>10.6μIU/mL fasting insulin) were less likely to adhere and lose weight on a low fat (LF) diet compared to insulin-sensitive (≤ 6.9 μIU/mL) participants assigned to the same diet.

There were no significant differences between insulin resistant (IR) and insulin sensitive (IS) participants assigned to LC-diet in relative adherence or weight loss. 

Is a low-fat diet for me?

Clinical trials comparing a variety of low to high carbohydrate diets demonstrate significant weight loss on any reduced calorie diet regardless of macronutrient composition. Ofcourse, this is based on adequate adherence to the dietary regimen, no diet will work if you don’t stick to it (Alhassan et al., 2008).

However, this study shows that adherence, and ultimate weight loss success, can be affected by your health profile and the diet that you choose.

As you can see, there is no BEST diet. What’s great for some isn’t so great for others!

For someone who has a high BMI and weight, a low-fat diet may make it harder and negatively effect the success of a weight lose weight. This may be explained by feeling less satiated and experience stronger metabolically driven urges to eat, which over time reduces adherence to a reduced calorie intake (Rodin, 1995; Ludwig et al., 1999; Shikany et al., 2011).

For example, if you are insulin resistance your blood sugar levels may spike and crash, this fluctuations can cause rapid changes in energy and hunger. This may mean you eat more and if you have low energy, you may miss workouts or not train as well.

Poor Insulin Sensitivity also means you have less dieting flexibility, if you have a few days off eating well on vacation and gain a ton of fat this may be partly due to insulin function (you can download my free 7 Day Insulin Sensitizing Protocol if you want to learn ways to improve this).

For someone who has a low BMI and weight along with a low body fat percentage, it seems that their adherence to a diet is not much different on either a low fat or low carb diet. Thus, they have more flexibility in choosing what diet approach they take to lose weight. Being able to diet down on more carbs may also come with other advantages, including:

  • Promote recovery, aiding with glycogen replenishment and reduced muscle sorness.
  • Produce insulin, driving nutrients to the cell (such as amino acids or creatine) and increase Muscle Protein Synthesis
  • Provide fuel, allowing you to train harder for longer.
  • Reduce muscle breakdown via decreasing protein breakdown or amino acid use as fuel.
  • Improve neural drive, helping reduce fatigue and increase power output or workout performance.


These results suggest insulin resistance status may affect dietary adherence to weight loss diets, resulting in higher recidivism and diminished weight loss success of IR-participants advised to follow LF-diets for weight loss.

As you can see, Insulin Sensitivity is an important factor in dietary flexibility, weight loss success, physique transformation and course, long term health and disease risk.


 Alhassan, S., Kim, S., Bersamin, A., King, A. C., & Gardner, C. D. (2008). Dietary adherence and weight loss success among overweight women: results from the A TO Z weight loss study. International journal of obesity,32(6), 985-991.

Ludwig, D. S., Majzoub, J. A., Al-Zahrani, A., Dallal, G. E., Blanco, I., & Roberts, S. B. (1999). High glycemic index foods, overeating, and obesity.Pediatrics103(3), e26-e26.

McClain, A. D., Otten, J. J., Hekler, E. B., & Gardner, C. D. (2013). Adherence to a low‐fat vs. low‐carbohydrate diet differs by insulin resistance status. Diabetes, Obesity and Metabolism15(1), 87-90.

Rodin, J. (1985). Insulin levels, hunger, and food intake: an example of feedback loops in body weight regulation. Health Psychology4(1), 1.

Shikany, J. M., Margolis, K. L., Pettinger, M., Jackson, R. D., Limacher, M. C., Liu, S., … & Tinker, L. F. (2011). Effects of a low-fat dietary intervention on glucose, insulin, and insulin resistance in the Women’s Health Initiative (WHI) Dietary Modification trial. The American journal of clinical nutrition, ajcn-010843.

About the author


Rudy Mawer, MSc, CISSN

Rudy has a 1st class BSc in Exercise, Nutrition & Health and a Masters in Exercise & Nutrition Science from the University of Tampa. Rudy currently works as a Human Performance Researcher, Sports Nutritionist and Physique Coach. Over 7 years he has helped over 500 people around the world achieve long last physique transformations.

He now works closely with a variety of professional athletes and teams, including the NBA, USA Athletics, World Triathlon Gold Medalists, Hollywood Celebrities and IFBB Pro Bodybuilders. If you would like to get in contact or work with Rudy please contact him on social media.

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