Weight Loss: What Does the Research Show?
Originally published Dec. 2, 2018.
Beginning of 2016, I'm in grad school, studying exercise physiology, working as a personal trainer, a graduate assistant with division 1 athletes, many people, myself included would consider myself pretty knowledgeable on the topic of fitness and nutrition. Yet, there I was, a little fatter than I wanted to be, trying a new diet to shed a few pounds and break my addiction to the almighty Mountain Dew and Twizzlers. The diet seemed a little counter intuitive to fat loss. I was eating a lot of bacon, beef and butter. All things loaded with fat and high in calories. I had heard a lot about it though and figured eating a ton of bacon sounds like a great idea so why not try for myself. Cut to one week later washing dishes in my tiny kitchen sink. Everything is greasy, all of my dishes, pots, pans, my hands, the door, the floor, I was slipping and sliding all over my apartment because of all of the grease from this high fat diet. I may be exaggerating slightly but that's how I felt. That was strike one for this diet. Strike two came from looking at my bank account. Eating steak, bacon and avocado all day, everyday was adding up quick. Strike three came when I realized I wasn't shedding any fat.
I share that dramatic story because I know many people try diet after diet and experience no results. Today I want to dig deep on a few popular diets to help you succeed in your weight loss efforts. Had I known at the time exactly how to do that diet properly it may have actually worked. For those who are unaware, the diet I was attempting above is the now famous ketogenic diet. That is one diet I'm going to take a deep dive into to let you know if it works and if it does, how to do it properly.
Before I get into the different diets I will save some of you some time who don't really care to read the full article. I completely understand so with that being said after getting into the research I came to two conclusions. One, nowhere near enough research has been done in the field of nutrition but it is a work in progress. Two, and something most people will find unfortunate is that there is not one diet, at least for now, that rules them all. In fact, here and here are links to a couple of reviews stating any diet can work as long as it is something you can follow. So knowing that any diet can work I'll still give you some insight into a few popular diets today.
A couple more things I feel are critical to know, first off, I am not a dietitian. Nutritionists are not dietitians and the YouTube celebrity that lost 100 pounds, while impressive, is not a dietitian. I always recommend discussing nutrition with a registered dietitian especially if you have a medical condition, they are experts. While I am not a dietitian, I feel that I have enough experience to properly research and discuss these topics but feel free to take this all with a grain of salt and look into it all yourself. One other thing you should know going into the article is the term macronutrients or "macros". Macronutrients are carbohydrates, protein and fat. Often times a diet will be based around macro ratios or percentages. This is simply referring to how many grams of each nutrient you are eating, which can play a major role in your body composition. There is obviously a lot more to them but that is all you need to know for now.
First up, the aforementioned ketogenic diet. I want to point to out that this article is focused on weight loss. Some of these diets, particularly the ketogenic diet have other potential health benefits that I wont get into. Going back to my intro above, the first time I tried a ketogenic diet I had no idea what it was. Like many people I run into, I thought I could just eat bacon and nothing else and that would suffice as a ketogenic diet. I won't say this often but I was wrong. Here is what a classic nutritional ketogenic diet should look like in terms of macronutrients, 5-10% of calories from carbohydrates, 20-25% from protein and 70-75% from fats. That means basically no carbs, things like bread, pasta and even fruit are nearly impossible to eat on this diet. My meat rich diet looked more like 2-5% carbs, 45-55% protein and 45-55% fat. While this is still high in fat and low in carb, the issue lies in the protein. Many people who try a keto diet intake far too much protein. The reason this is problematic is that your body converts protein into carbs via gluconeogenesis (for those so inclined here is a video explanation of this process). Once the conversion happens your body has no reason to utilize ketone bodies as fuel. What the hell are ketone bodies? Oh yeah, I forgot to mention those are important with this diet. When our human bodies are depleted of sugar (carbs) we turn to fat for fuel, the brain in particular has to utilize ketones when glucose is unavailable. Ketones are broken down from fatty acids. A large reason this diet has gained so much steam is because we hear that phrase use your fat for fuel and we get excited. While this is true, you are "burning" fat, it is still very easy to over consume and that is one major flaw with the diet. Because you are consuming fat, it could be stored very easily as fat.
One possibly very large benefit to being in a state of ketosis while trying to lose weight is its potential to maintain your basal metabolic rate, aka keep your metabolism as fast as possible (read the science here). Often times, your metabolism slows down while in a state of caloric restriction. When it comes to weight loss and looking sexy, body composition is really the key. Holding onto your muscle mass is critical to achieving an ideal body composition. I found conflicting research (here and here) when it comes to retention of muscle mass on a ketogenic diet so that is something you have to find out for yourself. I have dabbled with a ketogenic diet myself another time aside from my story above and in my experience it is not for me. It is far to restrictive to enjoy my life and the results were not great enough to warrant that. For some though, the restriction may be just the thing they need to lose weight.
Next up is a high protein/low carb diet. Quite a few diets can fit into this category and its a very common way to lose water weight quickly. A very popular diet is the Atkins diet which is what I will focus on. Protein, protein, protein. That is the focus here. The Atkins diet has four phases, which I found here.
Phase 1 (induction): Under 20 grams of carbs per day for 2 weeks. Eat high-fat, high-protein, with low-carb vegetables like leafy greens. This kick-starts the weight loss.
Phase 2 (balancing): Slowly add more nuts, low-carb vegetables and small amounts of fruit back to your diet.
Phase 3 (fine-tuning): When you’re very close to your goal weight, add more carbs to your diet until weight loss slows down.
Phase 4 (maintenance): Here you can eat as many healthy carbs as your body can tolerate without regaining weight.
For those of you who don't know, 20 grams of carbs is very low. I would imagine energy levels are extremely low in the beginning of an Atkins diet. Because your protein intake is so high your body probably doesn't enter a state of ketosis which is why I would assume energy would be low and you'll feel like shit. I've never tried an Atkins diet but I can attest to higher levels of protein resulting in weight loss. That being said I am unsure of the safety of very high protein with little to no carbs or fats. What I was seeing in the research was a lot of short studies which are not entirely helpful because one of the biggest problems with weight loss is maintaining the weight for the rest of your life. Atkins is a good example of what I see many people do. They dramatically cut carbs for about a month, lose a significant amount of weight and then in 2 weeks all of the weight comes back. This goes back to what I had mentioned earlier about having a sustainable diet. If you can only maintain a diet for a month it's not a good diet. Your body needs calories to function, when you limit it for so long you are bound to give in.
I will lump the whole 30 diet into this category of low carb because it is very restrictive when it comes to many common carbohydrate rich foods. I have heard from several people that they enjoy this diet and it worked for them. For those people, great, keep doing you. With that said here are my thoughts given there is no research done regarding the diet specifically. For those who don't know the whole 30 diet is a diet which calls for a person to abstain from sugar, legumes, grains, dairy and alcohol for a month. The claim is that these are all inflammatory foods and this diet gives your body a "reset". My first thought is scam, as is anything that uses terms like reset or detox. I can get into that at another time. After looking into it more and thinking about it, it may not be so bad. It is certainly good to get rid of some of those foods as they do cause inflammation as well as a host of other issues. My main concern with the diet is that there would most likely be a big lack of energy. If you can only eat meat, veggies and fruit you will have a very challenging time getting adequate calories throughout the day. As I have recently experimented with a ketogenic diet I believe the best approach to this diet would be to do it under the conditions of ketosis. You will simply not intake enough fruits and vegetables to get substantial carb intake for energy. Since you can consume oils though you can probably get into ketosis and have a much easier time. I really don't see this as a healthy long-term diet though because of the lack of calories.
Next on the list of diets is my personal go to and the one I recommend most often, macro counting. This is simply following specific ratios of the macronutrients. I particularly follow standards set by the USDA. While I know the man is always out to get us, I have found the recommendations set tend to work for most people if they can follow along. For those attempting to lose weight fast, which is everyone trying to lose weight, I let them try a diet of 35% protein, 45% carbs and 20% fat. The total calories depend on you specifically. This is a surprising amount of protein for most people and we end of cutting that back slightly. The way to track this would be to use an app such as MyFitnessPal. You input your food and it spits back to you calories and percentages of macros. While I personally use this method and find it affective many other's hate it because it takes some effort to use an app to input the food you have eaten. This goes back to diets working for you, if you hate tracking macros, it won't work. In my opinion, this diet allows the most leeway to slip ups. If you eat a pint of chocolate chip cookie dough ice cream you can input that into the app and work around what you have left.
Last but just as effective/ineffective is an intermittent fasting diet. What in tarnation is that? It is simply eating in a specific time window during the day. For example, an eating window could be from 6 am to 2 pm and the rest of the day you fast. For those late night snackers, this is probably a very helpful diet. I actually use this diet in combination with macro counting as I believe most people do and research done on IF uses specific macronutrient ratios. This will come as a huge surprise but when looking at research done on the diet I found mixed results. Some research (click me for research) shows IF made no difference in weight loss while other research (right here) shows otherwise. Like the ketogenic diet, there does seem to be some other benefits outside of weight loss but that is not why I am writing this.
When I decided to write this I really thought I was going to find a bunch of research and that I would be able to narrow it down to one supreme ruler of the diet throne. Unfortunately, like almost everything in life, there isn't a one size fits all approach. If you are someone trying to lose weight take a look at some of these diets and decide what can work but know going in, it takes some effort. Have a plan and try to stick to it.