Low fat high carb, low carb high protein, even when choosing whole foods, is their a proportion of macronutrient which are the carbohydrates, proteins, and fats that is best? For the last 50 years or so, many studies have evaluated diets based on the content of their carbohydrate, protein, and fat. Each macronutrient, in turn, has been blamed for the rise in obesity. Historically, out of an intuitive notion that fat must be making us fat, low fat diets became popular in the 1970s. Between 1980 and 1997, dietary fat as a percentage of total calories decreased from 41 percent to 37 percent. Anything low fat was considered healthy, including low-fat cookies and low fat ice cream. Despite many low-fat options hitting the grocery shelves, rates of obesity steadily rose. A closer look at the American diet during that time, shows that even though fat as a percentage of calories decreased, the total amount of fat we were eating didn't change. Instead, we began consuming more calories. In other words, we never really went low fat. What happened is that we became so focused on fat that we stop paying attention to other macronutrients. Many low-fat foods replace fat with unhealthy carbohydrates, sugars, and refined flours. In our intake of these processed carbohydrates and our total calorie intake soared. In response, many low carb diets became popular and since then, many different diets, including fad diets, continue to hit the market, each claiming to be the best. In 2009, researchers at Harvard tried to end the debate. They carried out the largest ever, highly regarded, randomized clinical trial, in which participants were assigned to diets with different proportions of fat, carbohydrates, and protein and were followed closely for two years. While the average weight loss from the various calorie balanced diets was three to four kilograms, the amount of weight loss was similar in all the groups. People on low carb diets did just as well as people on high carb diets and people on low fat diet did just as well as those on high-fat diets. While it may seem countered the popular perception, the authors concluded, and what has been seen in other studies, is that you can lose weight on many different diets, with different proportions of fat, carbohydrates, and protein. The key takeaways from this large Harvard study are, first, it's not the quantity but rather the quality of fat, carbohydrates, and protein that matters for weight loss and health. Higher quality or healthier fats, for example, are mono unsaturated or poly unsaturated fats rather than saturated or trans fats. Higher quality carbohydrates are ones that are from whole foods package with fiber. Such as vegetables, fruits, and legumes, rather than ones that are processed. In general, choosing whole foods matters more than worrying about your intake of protein, carbs, and fat. Second, the best plan for you is one that you can stick with long-term. One that matches your preferences, traditions, and customs. Don't look for programs that are so strict or so limiting that you can only follow them for a few weeks. In the Harvard study, participants that were able to stick to their healthful diet, no matter the proportion of protein, carbs, and fat lost the most weight. Observations from different cultural diets around the world reinforce these findings. In fact, some of the healthiest diets around the world vary dramatically in their proportion of each macronutrient. The Okinawan diet followed by the Japanese in this longevity hotspot is high in carbohydrates. On the other hand, the hearten waistline healthy dietary pattern followed by the people in Mediterranean countries as high in fat. Using genetics, however, the latest science is showing that there's a twist to these two major principles. In 2016, the same researchers that carried out the large Harvard study went back and re-evaluated how participants responded to the different diets based on whether they carried a particular gene that affects energy balance and fat metabolism. They observed that how each participant responded to the varying proportions of the fat, protein, and carbohydrates differed significantly based on whether or not they carry this gene. Therefore, well, among all people that follow a diet that is low carb or low fat, the average response is not significantly different. The response in each person does vary considerably. In other words, no healthy diets stands out as best for everyone. The diet that works best for each person can vary significantly based on our genes. Referred to as the weight-loss trap, this idea that each of us responds differently to different diets made the cover of Time Magazine in May 2017. Frustrating as the headline suggests, it's important not to miss the forest for the trees. It's not that there are no diet rules, and it's not that diets don't work, we all do better with a healthy pattern of eating with plenty of fruits and vegetables than with junk food and processed foods, no matter our genetic makeup. But within this theme of healthy eating, it may take some trial and error and persistence to find the proportion of fat or carb that makes weight loss more manageable and sustainable. In summary, don't give up if you don't lose any weight following the same plan that worked for your friends or family members. Failing several times is normal. Focus on eating clean, whole food, avoiding processed foods, and trying different proportions of protein, carbs, and fat. Eventually, you will be successful.