“What is the best diet for weight loss” is easily one of the top questions that fitness trainers get asked. This makes perfect sense when you consider the fact that weight loss is the number one fitness goal. Before I answer this question, I think it’s important to create some context around this question in order to better inform you.
To start with, let’s define ‘weight loss’. Most people (this includes you) aren’t necessarily interested in weight loss. Most people want FAT LOSS. This is a VERY important distinction. For example, you could cut off your leg and instantly lose pounds of body weight. Losing the wrong kind of tissue is far from ideal. Losing muscle will slow your metabolism down making maintaining fat loss far more difficult. A slow metabolism burns less calories than a fast metabolism. If fat loss is your goal you do NOT want a slow metabolism.
We should also define whether or not you want temporary fat loss or PERMANENT fat loss. Do you want to lose fat then gain it back or do you want to banish it forever? I would bet my house that the vast majority of you want long-term, life-long fat loss. No one wants to get caught in the cycle of losing and gaining excessive body fat.
Now that we are clear that you want PERMANENT FAT LOSS we are almost to the point where we can figure out the best fat loss diet. Before we dive into diets, it’s extremely important to understand that fat loss ONLY happens under the following condition: a caloric deficit. In order for fat loss to occur, you absolutely MUST be consuming LESS calories than you burn, or to put it another way, you MUST be burning MORE calories than you consume. Without getting too technical, just understand that this is a rule of physics. Energy does not get created out of nothing and it doesn’t get destroyed. It gets CONVERTED. When you eat food (energy) it gets turned into energy to be burned and used. If you eat more than the amount of energy your body needs, then your body stores the excess. On the flip side, if you are eating LESS calories than your body burns, then your body uses its energy stores (body fat) to make up the difference.
Rule number 1 with ANY fat loss diet: it must be made up of less calories than you burn.
This is what every single fat loss diet has in common. Doesn’t matter if it’s low carb, high carb, low fat, high fat, paleo, vegan, carnivore, keto, or ANYTHING ELSE. If it causes fat loss, it’s because the diet provided less calories than your body burned. Now that we understand that a calorie deficit is a must for fat loss, let’s look into other factors that can make a diet more or less effective.
Studies consistently show that a high protein diet is more effective for fat loss than lower protein diets. What is considered high protein? Roughly half your body weight in grams of protein to your body weight in grams of protein if you aren’t obese. This would be 70-140 grams of protein for a 140lbs woman or 100-200 grams of protein for a 200lbs male. If you are obese, use your lean body mass (fat mass minus lean mass). A high protein diet isn’t the only way - any diet that puts you in a caloric deficit will cause fat loss – but, high protein diets have been proven to preserve more muscle versus other diets (muscle burns a lot of calories) and high protein diets are proven to help with appetite control. Protein is also an essential nutrient meaning you NEED to eat protein just to survive. A high protein diet will help you eat less and keep (or gain) more muscle. All that being said, a diet containing much lower amounts of protein can be very healthy and you can still lose a considerable amount of body fat without eating lots of protein.
Throughout the ’70s, ’80s and most of the ’90s fat was blamed for heart disease, cancer, and the growing obesity epidemic. Our own government guidelines told us to not eat too many fats and especially saturated fats because they were “so unhealthy.” This turned out to be mostly false. Studies show that a high fat diet in the context of a diet that is low enough in calories to maintain a lean body is typically perfectly healthy. There are also a few examples of cultures that consume diets that are very high in fat who are also very healthy. The Inuit people of northern Canada and Alaska and the Maasai tribes of Kenya and Northern Tanzania consume most of their calories from animal fats and they both display incredible health. Of course, their diets are also relatively low in calories for their caloric energy output. Fats are also essential meaning you MUST consume a certain amount of fats just to maintain normal bodily functions and health.
Over the last couple of decades carbohydrates have gotten some bad press. They have been blamed for the obesity epidemic and for most of our modern chronic health problems. The science on carbohydrates doesn’t really back this up. There are numerous examples of long living societies and cultures that consume a good deal of their calories from carbohydrates. Okinawans are among the longest living people on Earth and they eat a diet that is largely made up of carbohydrates. How is this possible??? They don’t eat many calories. In the context of a diet that is high enough in calories to cause fat gain and obesity, carbohydrates can have devastating health effects, but in the context of a diet that is low enough in calories to maintain a relatively lean body they tend to not pose many health issues. Carbohydrates are not an essential nutrient meaning you don’t have to eat a single carb to survive.
Notice a trend? Most diets can be very healthy if calories are appropriate. Does this mean it’s all about calories? Are all foods healthy so long as calories are low? The short answer is no. There is one category of food that has been consistently connected to bad health and to fat gain. Heavily processed foods. These are foods that typically come in wrappers, boxes or have lots of hard to pronounce ingredients.
Heavily processed foods aren’t necessarily inherently unhealthy (although most are less healthy than unprocessed natural foods) but they do have one quality that makes them almost always a bad choice. They make us eat more. A lot more. In fact, studies show that people will eat 500-600 more calories per day on average when their diets are largely comprised of heavily processed foods. That is a ton of extra calories every week and this equates to pounds of fat on our bodies. This is because heavily processed foods are specifically engineered to make us eat more. Ever notice how you will eat cookies or chips far past the point of feeling full? Most of you know exactly what I am talking about. Heavily processed foods are the likely culprit for our modern obesity and health related issues.
The best diet for fat loss for you can be different than the best diet for the next person. It can be low carb, high carb, low fat, high fat, paleo, vegan, carnivore, keto, or almost anything else so long as it contains adequate amounts of the essential macro nutrients (proteins and fats) and so long as it is largely devoid of heavily processed foods. This is great news because it gives you lots of flexibility. I have trained individuals for over two decades and I have seen people succeed long-term with many different types of diets, but I’ve never seen long term success with a heavily processed food-based diet. Eat appropriate calories, eat the foods that make you feel best and stick to whole natural foods and your odds of long-term fat loss will be much better than the average fat loss orientated dieter.