If you have a medical condition that requires a specific diet, you should disregard this biohack, and ONLY follow your physician's or nutritionist's instructions.
Over a third of Americans are currently obese . Beyond simply being a public health crisis, widespread obesity—by virtue of comorbidities such as heart disease and diabetes— is a massive burden to our healthcare system. Public discourse on the issue ranges from "it's all genetic" to "fat people are just lazy," with health experts staking their claims against either fats or carbs. The truth is that once you have eliminated refined, processed foods—both low-carb and low-fat diets spontaneously reduce hunger and result in equal amounts of weight loss . And obesity isn't the result of laziness, it's a consequence of ordinary living in an unordinary EEA—the modern landscape of food. If every single financial transaction you made occurred inside the environment of a casino, chances are that you'd end up broke. Of course, not every single individual would end up that way, but that doesn't take away from the fact that the house always wins. You can learn how to count cards in blackjack or increase your poker-playing skills, but the best option for most people is to just leave the environment of the casino.
The problem isn't carbs or fat, it's carbs and fat together. In the last 200,000 years, there has never been a time where foods have contained high proportions of both of these macronutrients. For the most part, fruits are composed of carbohydrates, vegetables are composed of carbohydrates and protein, and meat/nuts are composed of protein and fat. Breast milk is a rare example of a food that contains both macronutrients in relatively equal proportions, with roughly 3.5% of energy coming from fats, and 7% coming from carbs. The carbohydrate and fat ratios of modern, refined foods are 7-8 times higher. If we want to be lean and healthy, we need to step away from the environment of modern food choices.
When mixed together, fats and carbs are ultra-rewarding, even to the point of being addictive 
Compared to calorically equal amounts of carbs or fat, fat and carbs together are much more desirable. This high-energy combination is extremely rare in our ancestral EEA, which was subject to the selection pressure of scarcity and famine. Thus, we've evolved an adaptation to pay special attention to it. The neurochemical effects of this fat + carb combination are similar to those of habit-forming drugs.
Carb and fat dilute protein, the "safest" macronutrient
The total percentage of macronutrients in a given food must add up to 100%. As you increase the percentage of fat and carbs, protein becomes diluted—it's relative percentage necessarily goes down. In this context, "safety" refers to two things. First, protein increases satiety to a greater degree than either fat or carbs . Both of the plates on the left contain the same number of calories. Which one will keep you fuller longer? The plate with more protein on it. The second reason for protein's "safety" is that you can eat as much as you want of it without gaining body fat . In one study, participants who were fed 4.4 g/kg of protein (this equates to 400g of protein for a 200 lb male, or 1600 calories) gained no body fat and experienced no negative health effects from this overfeeding . To sum things up, protein is "safe" because it's hard to eat too much of it, and even if you do, it's hard to gain weight from it. Biochemically, converting protein to usable energy in the form of glucose is an energetically expensive process. All of this flies in the face of the very common misconception is that "a calorie is a calorie."
It does, however, make perfect sense from an evolutionary perspective. Proteins are the highly desirable building blocks of life, and in the EEA, they are mostly found in animals that aren't looking to be eaten. For humans, hunting animals is hard work—especially when compared to picking berries. It simply wouldn't make sense for our metabolisms to evolve in a way where protein would preferentially be converted to or stored as energy, considering the relative abundance of carbs and fat—both of which are less essential than protein.
Mixing carbs and fat together causes a metabolic "traffic jam" 
Human metabolism is akin to an enormously complex Rube Goldberg machine that extracts electrons from chains of carbon molecules. This process is subject to regulation at nearly every step, with constant communication between the enzymatic machinery and their metabolic byproducts. Carbohydrates and fats are processed in different "lanes" which are connected by chemical signals. If everything is working correctly, lanes are sped up or slowed down in response to the relative amount of raw materials (carbohydrates or fat) that are entering the system. An influx of both carbohydrates and fats creates crosstalk that messes up the whole factory. Machines get conflicting signals, which causes all the lanes to get backed up. This damages the body's nutrient sensing systems and wreaks havoc on your metabolic efficiency. The result is that you need to eat more to extract the same amount of energy, and much of the extra food spills over into fat stores.
Fats in the morning, carbohydrates at night
Every time you wake up in the morning, your body is flooded with a cascade of hormones that act like a chemical alarm clock going off. Adrenaline and cortisol course through your circulatory system, causing a heightened state of alertness. At the same time, your body begins churning through its fat stores so that you can have the energy to get up and get moving . These "breakdown hormones" will stop working their magic in the presence of insulin, a "building hormone" which acts opposite to cortisol . Insulin is released by the pancreas in response to carbohydrates, but not fat. Thus, it is best to start out your day with a fat/protein breakfast, and end it with a carb/protein dinner .
To think about why this makes sense, let's travel back in time to the EEA in which we evolved to deal with. Humans are living in hunter-gatherer societies, and refrigerators won't be invented until thousands of years from now. For the most part, if you're going to hunt an animal and eat it, it's going to be in the daytime. This is your bolus of fat and protein. Once nighttime rolls around, it's time to eat whatever tubers and berries you've managed to gather throughout the day. These are your carbs. In this hypothetical scenario, most of your calories end up being ingested in the daytime. Recent studies support the health-promoting effects of this eating pattern .
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