Attempts at Objectively Defining Clean
A simplistic learning tool called the “Go, Slow, and Whoa” (GSW) food classification system was designed to help children and families make better food choices [13]. GSW was recently compared with the more sophisticated NRFI, and despite some differences, both methods closely corresponded with each other in terms of distinguishing energy-dense and nutrient-rich foods [14]. Although the two methods aligned fairly well, they also share similar out-dated ideologies. For example, sports drinks have a “Slow” designation, and whole milk is nailed as a “Whoa” food – brilliant, huh? Tuna canned in water is in the most favorable “Go” column, while fatty fish like salmon is not even listed. A final example is the listing of egg whites in the “Go” column, and whole eggs in the “Slow” column. Unsurprisingly, the government-issued guidelines are still stuck in the fat-phobic era.
Perils of Judging the Parts & Not the Whole
In the process of classifying foods based on nutrient density, the context of the foods within the diet as a whole is often lost. Attempts at defining nutrient density of foods on an individual basis, for the most part, have failed. Much of the classifications are out-dated at best, and counterproductive at worst. It would seem to be a simple matter of labeling foods with a high ratio of micronutrients to calories as nutrient-dense, and foods with a high ratio of calories to micronutrients as energy-dense. However, this simply is not the case. An energy-dense food can still contain more essential macronutrition and/or bioavailable micronutrition than a nutrient-dense, energy-sparse food. Another thing that tends to get ignored is that athletes with high endurance demands or high overall training volume would compromise their performance if energy density was neglected. Ultimately, it’s impossible to judge a food in isolation from the rest of the diet. Furthermore, it’s impossible to judge a diet without considering the training protocol, goals, preferences, and tolerances of the individual.
Dirty Fat Loss
Clean diets are commonly touted to produce more favorable body composition changes than unclean diets. In fact, some even claim that dirty dieting will not allow fat loss to occur. For weight or fat loss, concerns of a dirty diet used to be centered on fat intake. That’s no longer the case; carbohydrate has been receiving the brunt of the contempt lately. In light of the current sugar-phobic climate with an emphasis on fructose, the following studies deserve special attention.
First up, Surwit and colleagues compared the 6-week effects of 2 hypocaloric diets - one with 43% of the total calories as sucrose (table sugar), and one with 4% of the total calories as sucrose [15]. No significant differences were seen in the loss of bodyweight or bodyfat between the high and low-sucrose groups. Strengthening these results was the use of dual X-ray absorptiometry (DXA) to measure body composition. Furthermore, no differences in blood lipids or metabolism were seen between the groups. It looks like a more sugary intake still cannot override a calorie deficit.
Janeil knows a thing or two about eating right.
Next up is a recent study by Madero and colleagues, comparing the 6-week effects of a low-fructose diet (less than 20 g/day) or a moderate-fructose diet (50-70 g/day) mostly from whole fruit [16]. The moderate-fructose group lost significantly more weight than the low-fructose group (4.19 kg versus 2.83 kg, respectively). Notably, the moderate-fructose group lost slightly more fat, but not to a statistically significant degree. Unfortunately, body composition was measured with bioelectrical impedance analysis (BIA) instead of something more reliable like DXA. Nevertheless, bodybuilders afraid of fruit would have to admit that the dirtier diet prevailed in this case.
Trans fatty acids (TFA) have earned a lot of bad press for their adverse effects on biomarkers of cardiovascular health [17,18]. However, some research indicates that not all TFA are harmful. A distinction should be made between industrially produced TFA via hydrogenation of vegetable oils, and naturally occurring TFA in dairy and meat [19]. Vaccenic acid, the main form of TFA in ruminant fats, might actually lower the risk for coronary heart disease [20]. Currently, there’s no controlled human research specifically comparing the effects of TFA with other types of fats on body composition. In any case, the fitness-conscious population has nothing to worry about unless they start indiscriminately gorging on fast food, cooking with vegetable shortening, and pounding loads of processed/packaged pastries and desserts.
All-or-Nothing Dieting & Eating Disorder Risk
In 1997, a general physician named Steven Bratman coined the term orthorexia nervosa [21], which he defines as, “an unhealthy obsession with eating healthy food.” It reminds me of the counterproductive dietary perfectionism I’ve seen among many athletes, trainers, and coaches. One of the fundamental pitfalls of dichotomizing foods as good or bad, or clean or dirty, is that it can form a destructive relationship with food. This isn’t just an empty claim; it’s been seen in research. Smith and colleagues found that flexible dieting was associated with the absence of overeating, lower bodyweight, and the absence of depression and anxiety [22]. They also found that a strict all-or-nothing approach to dieting was associated with overeating and increased bodyweight. Similarly, Stewart and colleagues found that rigid dieting was associated with symptoms of an eating disorder, mood disturbances, and anxiety [23]. Flexible dieting was not highly correlated with these qualities. Although these are observational study designs with self-reported data, anyone who spends enough time among fitness buffs knows that these findings are not off the mark.
Applying Moderation: The 10-20% Guideline
For those hoping that I’ll tell you to have fun eating whatever you want, you’re in luck. But, like everything in life, you’ll have to moderate your indulgence, and the 10-20% guideline is the best way I’ve found to do this. There currently is no compelling evidence suggesting that a diet whose calories are 80-90% from whole & minimally processed foods is not prudent enough for maximizing health, longevity, body composition, or training performance. As a matter of fact, research I just discussed points to the possibility that it’s more psychologically sound to allow a certain amount of flexibility for indulgences rather than none at all. And just to reiterate, processed does not always mean devoid of nutritional value. Whey and whey/casein blends are prime examples of nutritional powerhouses that happen to be removed from their original food matrix.
Use the 10-20% discretionary intake rule and enjoy life a bit.
The 10-20% guideline isn’t only something I’ve used successfully with clients; it’s also within the bounds of research. Aside from field observations, there are three lines of evidence that happen to concur with this guideline. I’ll start with the most liberal one and work my way down. The current Dietary Reference Intakes report by Food & Nutrition Board of the Institute of Medicine lists the upper limit of added sugars as 25% of total calories [24]. Similarly, an exhaustive literature review by Gibson and colleagues found that 20% of total calories from added sugars is roughly the maximum amount that won’t adversely dilute the diet’s concentration of essential micronutrition [25]. Keep in mind that both of these figures are in reference to refined, extrinsic sugars, not naturally occurring sugars within whole foods like fruit or milk. Finally, the USDA has attempted to teach moderation with their concept of the discretionary calorie allotment, defined as follows [26]:
“…the difference between total energy requirements and the energy consumed to meet recommended nutrient intakes.”
Basically, discretionary calories comprise the margin of leftover calories that can be used flexibly once essential nutrient needs are met. Coincidentally, the USDA’s discretionary calorie allotment averages at approximately 10-20% of total calories [27]. Take note that discretionary calories are not just confined to added sugars. Any food or beverage is fair game. The USDA’s system is still far from perfect, since it includes naturally-occurring fats in certain foods as part of the discretionary calorie allotment. This is an obvious holdover from the fat-phobic era that the USDA clings to, despite substantial evidence to the contrary [28].
It’s important to keep in mind that protein and fat intake should not be compromised for the sake of fitting discretionary foods into the diet. In other words, make sure discretionary intake doesn’t consistently displace essential micro- & macronutrient needs, and this includes minimum daily protein and fat targets, which vary individually. This may be tough to accept, but alcohol is not an essential nutrient. Its risks can swiftly trump its benefits if it’s consumed in excess, so it falls into the discretionary category.
10% Versus 20%
Another legitimate question is why I’ve listed the discretionary range as 10-20% rather than just listing it as a maximum of 20%. This is because energy balance matters. In bulking scenarios, maintaining a 20% limit could potentially pose health risks that are already elevated by the process of weight gain, which in some cases involves a certain amount of fat gain. Conversely, weight loss tends to be an inherently cardioprotective process, independent of diet composition [29]. So, the 20% limit is more appropriate for those either losing or maintaining weight. Those who are gaining weight but want to play it safe should hover towards the lower & middle of the range (10-15%). Another factor that can influence the upper safe threshold is physical activity level. I’ll quote Johnson & Murray in a recent review [30]:
“Obesity and metabolic syndrome are rare among athletes, even though dietary fructose intake is often high, underscoring the robust protective role of regular exercise.”
In the above quote, you can substitute any controversial food or nutrient in place of the word fructose, and the same principle would apply. A greater range of dietary flexibility is one of the luxuries of regular training. Sedentary individuals do not have the same level of safeguarding from the potentially adverse effects of a higher proportion of indulgence foods. And just in case it wasn’t made clear enough, 10-20% indicates the maximum, not minimum discretionary allotment. If someone strives to consume 0% of calories from any food that’s been processed or refined from its original state, then that’s perfectly fine – as long as this is the person’s genuine preference, and not a painful battle of will. I’d also like to make it clear that there is still plenty of grey area in the study of dietary effects on health. As such, the nature and extent of the miscellaneous or rule-free food allotment is a delicate judgment call. In this case, it’s wise to keep scientific research at the head of the judging panel, but don’t ignore personal experience & individual feedback.
