As promised a while ago, today I'm going to talk about the three diets that not only work, but also make sense. Being a physician and knowing a fair bit of biochemistry and physiology, I often cannot help it and not to hate some ideas out there on how to lose weight as they simply do not make any sense and in many cases, they are simply detrimental to those who adopt them. Having a critical mind doesn't always help much either in such cases, but today I'd like to use it for a good cause and I will talk about the three approaches that in my opinion are scientifically solid and are meant to deliver good results.
Fundamentally, these approaches are based on changing your diet in terms of quantity, quality and timing of your food intake in order to change your metabolism and to make your body use its inner resources a.k.a. fat to support your daily activities.
Let's start with quantity - it's the simplest and the most straightforward approach. The idea is based on the fact that we all have to use certain amount of energy to sustain ourselves. This amount can be calculated - there are several formulas that allow for calculating our basal (BMR) or resting metabolic rate (RMR) i.e. the amount of energy we need to spend on daily basis in order to maintain our bodies. Also, there are several coefficients that can be applied to BMR in order to calculate our daily energy expenditure based on our level of activity. We have it in the toolbox section for you to use. Knowing the total daily energy expenditure (TDEE) we can manipulate our food intake to create caloric deficit, which will reflect our spending more energy than we are getting from nutrients. Thus, in order to survive, our body will have to use our energy deposits - first glycogen and then adipose tissue (fat).
The pros of this approach are clear - it is simple and it's quite easy to get into a caloric deficit. All you have to do is reducing your food intake. And you still can have your favorite foods, but in limited quantities.
At the same time this approach has two major flaws. First, it might be quite time consuming to obsessively count your calories and a lot of people find it difficult. Also, in many cases, it's simply impossible, say, when you eat out, especially at some dinners when you do not order your food, but rather have it served and no one seems to know the nutritional value of the dishes. Second problem, and the main one in my opinion, is that unless we are talking about low-calorie low-carbohydrate diet, we are consuming lots of carbs. Carbs cause insulin release and effectively send our body on the path of storing energy whereas caloric deficit dictates that it should use that storage. So, if we omit all the biochemical theory here - we end up having fluctuations of glucose levels and when they are low we are craving food/carbs and end up being hungry most of the time.
As a side note, there is this concept of our bodies slowing down metabolism when fasting to a point of feeling very lethargic and depressed. I have a number of objections to this idea, but I think it deserves a separate discussion.
The second approach is based on manipulating the quality of food we consume, specifically, lowering the amount of carbohydrates. This approach was popularized by Dr. Atkins (though it was known for a while before him), and is the core principle behind several other diets. It does make sense as carbohydrates cause insulin release, which is one of our major storage hormones - one of its main functions is lowering blood glucose levels by either storing it as glycogen or by converting glucose into fat and storing it as such. If we eliminate carbohydrates from our diet, our body still has to maintain steady glucose levels for at least 2 tissues - red blood cells and the brain (though it can switch to ketones after a couple of weeks of low-carb dieting). In absence of carbohydrates and insulin our body quickly uses up glycogen (glucose storage) and turns to fat and proteins for energy. The main source of energy is of course fat - our body mobilizes fatty acids, transforms them into ketone bodies and uses them as energy. Again, it might take up to 2 weeks for us to adapt, a process called ketoadaptation.
The main benefit of this approach is that you don't have to count calories, but instead you have to significantly restrict your food choices. Dr.Atkins and many of his followers state that you may consume virtually any amount of low-carbohydrate food and your body will still keep burning fat due to the hormonal changes in metabolism. I was not able to find a single study that would support this particular claim, but I did find several anecdotal reports of people using high-calorie low-carbohydrate diets and still losing weight or at least not gaining it. Another benefit is that since you will not have substantial drops of your glucose levels and will consume a lot of food, you will not be desperately hungry most of the time.
The major disadvantage of the diet is that you will have to say goodbye to a lot of things, some of them might be your favorite foods. Also, given that it takes up to 2 weeks to adapt to a low-carb diet, every cheat will tremendously hinder your progress. Yes, having a slice of pizza might stop your weight loss for at least several days! Also, going to a restaurant or attending parties, luncheons or any other events where food is served might become a torture as you will be tempted to try some foods with questionable carb counts. I struggle pretty much every time I go out or stay at a hotel as carbs are abundant and ubiquitous and finding a low-carb meal sometimes is not even possible. In many cases you have to explain to everyone what you're doing and why and there is always someone who believes that you "don't have to do it" or that "you need carbs" or says that "you have to indulge yourself" or "one bit won't hurt" etc. If you tried it you know what I'm talking about, it is difficult at times, but it is a very effective way to lose weight (tested on myself multiple times).
The last approach is based on changing the timing of your food intake. Specifically, we take rather long breaks in food intake to allow our bodies to process food in an effective way and to trigger the release of hormones that are promoting fat loss. This approach is well known as intermittent fasting.
The idea is that if you don't consume any nutrients for a certain period of time it will shift your hormonal balance towards fat burning, mainly due to a surge of growth hormone during the fasting period. This idea is quite sound from the biochemical standpoint. Growth hormone is implicated in a number of processes that involve tissue reparation (energy consuming) and fat mobilization and it is indeed increased when people are fasting as well as during deep sleep, so going on short-term fasts should help with weight loss.
This approach works really well for some people whose daily routine allows for it. A good example would be skipping breakfast and lunch and having only dinner so that effectively you have a surge of growth hormone at night when you sleep and then this surge is extended throughout the day as you fast. This effect is enforced by working out during the fast. You can find some evidence of this approach working for some athletes as well as some studies investigating the effects of intermittent fasting on weight loss and performance.
At the same time, the evidence that I found suggest that intermittent fasting might not be significantly better than simple calorie restriction and thus it effects are more likely due to calorie restriction rather than to timing of food intake. I'll elaborate on it in a separate blog.
In addition, there are also several diets I'd like to mention as in my opinion they are just variations of these three approaches such as for example Weight Watchers that are helping you to count points instead of calories or carbs. We spoke about Atkins, but there are other diets that fall into the low-carb category such as ketogenic diet, paleo diet, Dukan, South Beach diet etc. You might have heard of the Warrior diet, which seems to be essentially a variant of intermittent fasting etc. Also, there are vegetarians and vegans who do not consume animal products and, thus, would fall into the category of a qualitative diet, but effectively you would lose weight only if you consume less calories than you spend. Same applies to people who are eating only organic foods.
While these diets were worth mentioning, the basic three approaches are essentially all you need to know to build your own nutrition plan. I will make an effort to speak in more detail about each and every diet listed today in my future blogs.