flexible dieting

Flexible dieting is a method of regulating food intake that allows the dieter to enjoy a variety of foods within a balanced diet while working towards their weight and body composition goals. Recent technologies such as calorie and nutrient tracking applications and online nutrition information databases make flexible dieting simple.



IIFYM is an acronym that stands for “If It Fits Your Macros”.  It is an alternate title for flexible dieting that has been popularized by social media. The expression is somewhat misleading as it implies that macronutrients are the only important aspect of diet, which we know to be untrue.



Nutrients are food chemicals that allow organisms to thrive. Macronutrients are energy-containing nutrients that are consumed in bulk.  The five macronutrients are protein, carbohydrates, fat, alcohol and water.  Micronutrients, cofactors for metabolic reactions, are those consumed in relatively minute amounts – vitamins, minerals and electrolytes. Together, macro- and micronutrients drive metabolism.



Flexible dieting has been shown to be more effective than rigid diets. Flexible dieting is associated with less overeating, lower body weight and better mood.¹  Rigid or strict dieting is associated with disordered eating and higher body weight.²

Know what your body is getting and what it needs in terms of nutrients.  Tracking your food allows you to know what you are putting into your body with regards to nutrients proportions, total caloric intake, etc.  By tracking food according to macro- and micronutrient goals, you can be confident that you are consistently & efficiently nourishing your body.  Tracking also gives insight on macronutrient profile and micronutrient and energy density of foods.

Be in control of your metabolic rate. By tracking your caloric intake and body weight, you are able to assess your metabolic rate. Once you find the number of calories that maintain your weight, your "maintenance calories" or caloric baseline, you know that any increase will cause weight gain, and any decrease will cause weight loss. You don't require blindly "eating clean" or following a restrictive meal plan. Your metabolic rate and diet - and thus your goals - are in your control.

The problem with traditional clean eating and pre-contest meal plans.  In the case of competitors, "clean eating" pre-contest diets are typically limited to very few types of food and tend to be excessively high in protein and fibre.  This often results in deficiencies in one or more dietary component: essential fats and micronutrients due to lack of food variety and malabsorption caused by high fibre and insufficient dietary fat. The low calorie, low fat, and/or low carbohydrate nature of clean diets may also negatively impact training performance³, mood², and sex drive⁴ due to decreased energy and/or hormonal levels.

Enjoy a variety of foods.  Flexible dieting allows you to enjoy a variety of foods, including those considered unconventional for bodybuilders/dieters, without sacrifice of body composition goals.  

Be socially flexible. It's well-accepted that food and socializing come hand-in-hand. Flexible dieting makes it much more convenient to socialize: eating outside of home does not have to be a cause of stress, an automatic "cheat" meal, or uncomfortable if you opt for your prepared meal.  With a little planning and practice, the flexible dieter can take advantage of restaurants' nutritional facts or estimate food content in order to fit social meals to their daily target macronutrients.

  1. Smith, C., Williamson, D., Bray, G., & Ryan, D. (1999). Flexible vs. rigid dieting strategies: Relationship with adverse behavioral outcomes. Appetite, 32(3), 295-305. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10336790

  2. Stewart, T., Williamson, D., & White, M. (2002). Rigid vs. flexible dieting: association with eating disorder symptoms in nonobese women. Appetite, 38(1), 39-44. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10336790

  3. Phillips, S., Moore, D., & Tang, J. (2007). A Critical examination of dietary protein requirements, benefits, and excesses in athletes. J Sp Nutrition, 17, S58-S76. Retrieved from http://journals.humankinetics.com/AcuCustom/Sitename/Documents/DocumentItem/9898.pdf

  4. Volek, J., Kraemer, W., Blush, J., Incledon, T., & Boetes, M. (1997). Testosterone and cortisol in relationship to dietary nutrients and resistance exercise. J Appl Physiol, 82(1), 49-54. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/9029197