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Two Fairy Tales:
"I barely eat" - statement often uttered by the Average American woman, often followed by "I'm always dieting" or "I've been dieting for years and can't lose weight." Case study 1: Woman in her 30s Height: 5'4" (average American adult female height, CDC 2016 demographics data) Weight: 170.6 lbs (again average American adult female weight, CDC 2016 demographics data) Estimates that she eats an average of 1200 kcal/day Works out 3 times/week, 10k steps per day Vs. Case study 2: Woman in her 30s Height: 5'4" Weight: 120 lbs (on the leaner side of "Healthy Weight Range" by BMI for this age/gender/height) Estimates that she eats an average of 3000 kcal/day Works out 5 times/week, 10k steps per day Is either of these described case study scenarios possible? Yes. Is either of these scenarios likely? No. Why do I classify these as generally "fairy tales": A smaller body requires less energy and a larger body requires more energy. This math has been tested in lab settings with carefully controlled calorie intake and expenditure. This is where calorie calculations come from. A coach or other fitness professional will calculate your BMR (Basal Metabolic Rate) and your TDEE (Total Daily Energy Expenditure) and will estimate your caloric needs from there depending on factors like your age, height, gender, and activity level. These formulas are easily searchable and you can use them yourself if interested. Here's one of the most widely used formulas for calculating BMR (Harris Benedict equation): Women: BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) – (4.330 x age in years) Men: BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) – (5.677 x age in years) Here's one of the most widely used formulas for calculating TDEE (Harris Benedict equation): Women: BMR = 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) - (4.676 × age in years) Men: BMR = 66.5 + (13.75 × weight in kg) + (5.003 × height in cm) - (6.75 × age in years) If you haven't taken a math class in a while, there are a bunch of free calculators out there that will do the math for you and will even convert your weight and height if you have those measurements in lbs and inches vs. kg and cm. Here's a link to one to get you started: https://www.calculator.net/bmr-calculator.html The link above will give you adjustments based on activity level as well. So, getting back to our fairy tale scenarios. Try plugging in the case studies above and you'll see what I mean about these scenarios being unlikely. In Case Study 1, the average weight American woman described claims to be consuming low-calorie for a prolonged period of time, say 1200 kcal/day on average. That's a very unlikely scenario because at a weight of 170 lbs, 1200 kcal would most likely be a calorie deficit for this person. On the other hand, in Case Study 2, the fitspo gal claims to be consuming, say 3000 kcal/day on average. This is also a very unlikely scenario because at a weight of 120 lbs, 3000 kcal would most likely be a calorie surplus for this person. Case Study 1 (average American) will say: broken metabolism, metabolic adaptation, bad genetics, hormones Case Study 2 (fitspo) will say: active lifestyle, fixed metabolism, *all this muscle*, sleep, water, just have to want it hard enough These "explanations" don't make sense. Fitspo doesn't have enough muscle to make up for such a huge calorie intake relative to size/weight. Average American may be experiencing metabolic adaptation in that she is moving less as she consumes less calories whenever she attempts to diet, but even at a pretty sedentary activity level, a sustained 1200 kcal/day intake should produce weight loss in this individual. As described and earlier, we have equations that can help estimate intake ranges based on weight, age, gender, height, and activity level. The math doesn't math for these two scenarios described above. How many extra calories does having more muscle burn? Well, we do have some research on this to draw from - muscle is metabolically active in that it burns an estimated 4.5-7 kcal/lb per day (Elia, 1999). So, if you were to pack on 10 lbs of muscle over the next 5 years (no small feat!), you would be able to burn up to... wait for it... 70 extra calories per day! Yeah. Kind of underwhelming right? So, no. Building some muscle is not a miracle hack for getting to eat tons of food. Now, the act of training/bodybuilding + eating a higher protein diet will both also burn more calories than if you weren't doing those things. This is why, no matter what your starting point is, if you seek to get leaner and more muscly, a progressive overload training program with a high-protein diet will probably help you on your way. And on the other front, if you notice that weight loss slows down for you when you attempt a relatively low calorie diet (whatever that is for you specifically), you may want to consider the possibility that you are slowing down, as in moving less, in response to intaking less food. Some people are more responsive to decreases in calorie intake and will start moving less spontaneously (out of your control) in the body's attempt to maintain weight. For a waaaaaay more detailed explanation of this, please check out Layne Norton and Peter Baker's classic book: "Fat Loss Forever". With all this, there's also a really strong possibility in both case studies that the person estimating their intake and/or activity level has made an error or mis-calculated. People are notoriously bad at estimating their own calorie intake and activity level. So, we just do the best we can in our flawed human way. Why does any of this matter? The only farther-reaching issue I see with these two fairy tale scenarios being perpetuated is that the Fitspo scenario (Case Study 2) makes the Average American (Case Study 1) feel like she's missing out on some big secret or is just really really really unlucky genetically. Remember that the rules still apply to everyone in CICO (Calories In Calories Out). There's no magic hack. I will tell you that I've been both of these weights from the case studies above. I'm 5'4" too! I promise you that I was eating more calories on average when I weighed 170 lbs than I was when I weighed 120 lbs. Be careful comparing your numbers to other people. You may not be seeing the whole picture. That shredded girl you admire who eats "so much" may be working out twice a day and/or may be moving around like crazy most of the time with fidgeting, blinking, arm movements, pacing and so on. Some people respond to a calorie influx by spontaneously moving more to such an extent that it negates what would have been a surplus if their movement pattern had remained constant. This isn't magic, it's just an increase in NEAT (Non-Exercised Activity Thermogenesis). If you see yourself as the Average American in the scenario described above and want to make some changes that stick this time around: try eating more satiating foods, including more protein and fiber in your diet, and increasing your step count. I know it can be really discouraging when you've tried very low calorie diets before (like 1200 kcal for an average sized woman) and have been able to stick to your low calories for a little while only to fall off hard after you get burnt out. Why not try targeting something more manageable like shooting for maintenance or a moderate calorie deficit (if fat loss is your goal) + making some healthy lifestyle changes (like prioritizing lifting, making more of your food at home, incorporating more veggies, and so on). If you don't know where to start, I would recommend looking up "TDEE calculator" in your search engine or using the link above to get a general idea of where your daily kcals would fall for each phase or goal (maintenance, cut, or build). Hope this helps add some clarity! - Julie References: Elia, M. “Organ and Tissue Contribution to Metabolic Weight.” Energy Metabolism: Tissue Determinants and Cellular Corollaries. Kinney, J.M., Tucker, H.N., eds. Raven Press, Ltd. 1999. New York: 61-79.
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