Food: How Much to Have of What

• In today's modern age of information overload, there is no lack of debate about any topic you name, especially food. And, not dissimilar from other debates, the increase of information available has only further obscured the answers. Thankfully, the National Academic Press released for us a comprehensive manual of Dietary Reference Intakes (https://www.nap.edu/read/10490/chapter/1) to try to makes sense of all the variant beliefs out there. The contributors went out of their way to consider the best of research, even when experts disagreed greatly. Its free. It doesn't exist behind an academic paywall. But it's a tome, which I acknowledge means most people will refuse to wade through it. Thus, I'll summarize certain points and other related studies to try to help the layperson consolidate the focus into extreme concision.
  


• Each macronutrient (dietary fat, carbohydrates, protein and alcohol) is more than a big enough subject to tackle on its own. Whole books can be and have been written about an individual nutrient. So I am going to do my best at abbreviating the science. Vitamins, minerals, phytonutrients, cholesterol, and others we'll leave aside for now.


• Dietary fat:


• Every cell membrane is partially made from a fatty acid. We need fat. Your body manages all of your hormones, their production, balance, and regulation in large part from SATURATED fats. Therefore, we need some saturated fat. Though it's long been vilified, saturated fat has no good alternative in various human organ systems. From the hormone which regulates blood pressure to the hormones which make us fertile, we rely on saturated fats. Removing them from the diet raises risk of many chronic conditions.


• But how much to have?


• The DRI cautiously stood back from giving a gram per kilo recommendation for saturated fats. The authors did, however, recognize the necessity of saturated fat for all of the aforementioned and protein function and DNA transcription (p. 425). They also fessed up to the fact that low fat diets stunt growth (p. 437) and appear to increase risk of cardiovascular disease (p. 437-438) and correlate with digestive disorders (p. 438). They did a remarkable job of analyzing different specific fatty acids and dietary concentrations, concluding that many fats can be synthesized in the human body from others. Ultimately, the DRI conceded defeat, stating that dietary fat is too complex and too multifactorial to make blanket recommendations for adults. Some studies found that active adults have had beneficial outcomes at over 60% of daily caloric intake derived from fat and infants likely need at least 30 grams per day.


• A maximum intake or over-consumption level cannot be set, because it is unclear when, if ever, the dietary fat is causal in adverse outcomes (p. 481). The contributors safely stated that people can consume 20-45% of calories from dietary fat (p. 771). For someone on a 1,200 calorie program, that could be as low as 27 grams. For a large active adult on a 4,000 calorie program, that could be as high as 200 grams. It's a wide range. But it's non-controversial and well-considered.


• Dietary carbohydrates:


• The bad news for most readers is that the scientific consensus and all research can be summarized as follows: "the lower limit of carbohydrate intake compatible with life is apparently zero (p. 275)." The DRI did go on to approximate adult intake to 100 grams per day, which is a very broad and bland number when you consider the variance of activity and body mass for adults. The nonspecific nature is due to the fact that we can get all of our energy needs from fat and protein. Anything else which carbohydrates do in the body we can derive from protein.


• So, technically, if your fat and protein intake is sufficient, your carbohydrate need is zero... ALMOST.


• There is a subset of carbohydrates, fiber, which should not be zero. We don't know what it should be, since we cannot measure blood levels of something which is indigestible. Thus, the DRI again backed away from a direct recommendation other than we probably need some (p. 362).


• That said, there is quite a bit of evidence that diversity of gut flora, specifically the anaerobes bacteroidetes, play a causal role in health and weight loss (https://www.scientificamerican.com/article/how-gut-bacteria-help-make-us-fat-and-thin/). And these beneficial bacteria feed on resistant starches and fiber to the tune of proliferation (https://academic.oup.com/ajcn/article/101/1/55/4564325). Still, we only know that people experience benefit beyond 25 grams of fiber or so. We have no idea what the optimal level or maximum intake is.


• Dietary Protein:


• Protein does A LOT. It is the set of instructions for just about everything. It makes our nervous system possible. It accounts for 70% of our bone tissue. 100% of our immune system communication is protein. The list is pretty much endless. Protein is so essential to life that scientists, hoping to uncover how life began on Earth, propose that all life must've begun with either a sort of RNA-world or the primordial self-replicating PROTEIN (https://www.scientificamerican.com/article/life-rsquo-s-first-molecule-was-protein-not-rna-new-model-suggests/). And then, of course, protein does all the stuff people already know, like muscles and tendons and ligaments and skin and hair and nails.
  


• There's a solid consensus around an absolute floor of 0.8 grams of protein per kilogram of body weight per day (p. 589). Keep in mind this is for basic survival. Also, this is counting on an aggregate of complete protein (i.e. - all essential amino acids); thus, many plant sources don't count gram for gram. They are incomplete. And, in my experience, most people are woefully inadequate even to this standard.
  
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• Weight loss studies, on the other hand, show strong favor for 1.2g/kg/d as a floor with benefit all the way up to 2.4g/kg/d (https://academic.oup.com/ajcn/article/103/3/738/4564609). Again, this leaves us without an exact number for optimal wellness, so much as a range.
  


• While it is true that people with severe kidney damage have to be careful of high doses, healthy individuals have tolerated intakes as high as 2.8g/kg/d (https://www.ncbi.nlm.nih.gov/pubmed/10722779) or more with no kidney stress or adverse reactions. For a 220lb athlete, this is 280 grams or more of protein in a single day. To help the reader quantify, that's an amount you would find in almost three pounds of chicken breast or almost four pounds of ground beef. If you follow someone like the Rock or larger competitive athletes, you'll soon discover that they eat 60 ounces or more of high protein sources daily.
  


• Dietary Alcohol:


• Yes, it provides energy (p. 108). Also, its effects are well-known at every single dosing (https://en.m.wikipedia.org/wiki/Blood_alcohol_content). Strictly speaking, it is unnecessary to human survival; and it likely inhibits optimization of health and fitness. Plus, it has a well-defined lethal dose, which makes it completely unlike any other macronutrient.


• Summary of Lower And Upper Boundaries:


• There are obvious risks for all individuals whose fat intake is less than 20% of their daily calories, and/or whose daily protein intake is less than 0.8 g/kg/d. There are obvious risks to sedentary individuals whose caloric intake exceeds 45% from fat, and/or whose macronutrient intake exceeds 100 grams per day from carbohydrates.
  


• Fiber content should probably be 20-60 grams per day, but maybe more if an individual can tolerate it. Other carbohydrates are unnecessary, but can be dosed according to activity and goals. I've seen very active athletes tolerate hundreds of grams of carbohydrates. But the average individual cannot. In my coaching experience, some people need night time starches or sugars between 15-25 grams to balance serotonin and improve sleep. Of course, don't forget that this can be cleaved and synthesized from 30-50 grams of protein.


• Weight loss efforts don't seem to have good efficacy under 1.2 - 2.4 grams of protein per kilogram of body weight per day.


• Activity, hormone balance, age and body composition drive these variables. So I understand the hesitancy to make precise recommendations. If we consider the inactive or low activity individual, we may place some lower limits with confidence.


• If you weigh 110lbs, then you should eat at least 20 grams of fiber daily, at least 65 grams of protein daily, and at least 30 grams of fat daily. Alone, this is inadequate food intake. Establishing additional intake would be contingent on factoring in activity, compliance, calculated metabolic rate and desired growth or loss. That is, for a 110lb individual aiming to maintain body mass, we would start by measuring metabolic rate, which could well be potentially around 1340 calories. Right off the bat, this individual would need an additional 810 calories from fats, carbs and proteins just to maintain. If they want to lose, the recommendation would be less. If they want to gain, the recommendation would be more. Activity and compliance have to be accounted for as well.


• If you weigh 220lbs, double the amounts above. If you weigh 330, triple them.