Weight gain, maintenance and loss are solely dependent on whether we take in more energy than we expend.[1] This begs two questions: How do reduce the amount we take in, and how do we increase the amount we expend? This post will try to answer the first—that is, what kind of foods we should eat, and how much.

While a lot has been written on the topic and a lot of people are trying to make money with various diets, the common problem is that “under free-living conditions, the main determinant of long-term fat loss seems to be how well you stick to a diet, not which diet you choose.”[2] Hence, any look at diets should keep in mind that it will not be used in a clinical, fully-controlled environment, but by normal people out there who have a life and other things on their mind than to constantly worry about their food.

This post will try to first give a rough introduction to the major nutrients food is made of to help you understand what you eat, why, and how it affects your body. The second part will try to help you find a way to know how much you can eat, both to help you restrict yourself but also to give you the ability to feel good about the food you eat. The last part will then give an overview of recommended food compositions.

Nutrients

Nutrients are the basic building blocks of food. For losing weight and especially fat, the important ones are the so-called macro nutrients, which make up the majority of food. They are the ones that provide energy to the body. Your body can convert nutrients into whichever form it needs, and consequently the exact composition of these nutrients does not have a great effect on fat loss.[3]

There are also some other nutrients, in particular minerals, vitamins and water that all support the metabolism, but do not provide energy and hence do not affect weight. Because this series is about weight and fat loss, I’ll not go into those.

Fat

Fat is the long-term energy storage of organisms. We want to lose fat because our body has stored too much energy that way, but that does not mean we want to lose all of it. Fat is actually rather important to a healthy body.[4] Still, in food, fat provides a large amount of energy per mass (9 kcal/g), which is why we in general want to keep it somewhat low.

There are a number of types of fats, or rather, fatty acids. The two most relevant ones are saturated and unsaturated fats. Nutrition science has some evidence that unsaturated fat is more healthy than saturated fat, so do prefer unsaturated if possible.[5] Those are usually fats from plants, while saturated fats are from animals.

Carbohydrates

Carbohydrates is the nutrient from sugar, which also comes from grain products like pasta, bread, potatoes, rice, and fruits. It is a short-term energy source with less energy per mass than fat (4 kcal/g).

Whole grain products as a source for carbohydrates seem to be generally more healthy and associated to lower BMI levels so should be preferred.[6] This is not uncontroversial, though,[7] and contrary to popular belief, they are not necessarily related to lower levels of hunger.[8]

Carbohydrates have come into discredit based on certain claims about their effects on the metabolism, spurring the creation of “low-carb diets” that supposedly will make losing fat faster or easier. Scientific studies were unable to confirm this claim. The various attempts to explain how carbohydrates supposedly harm us have been thoroughly debunked.[9] Especially the fear of insulin some of these diet advises give is completely unfounded.[10] Additionally, in various studies, weight loss was entirely dependent on the total calorie intake, regardless of the composition.[11] A simetimes reported higher weight loss on low-carb diets might be because of an excess loss of water.[12]

Protein

Protein is the last macro nutrient that provides energy to the body (4 kcal/g). It is found in eggs, cheese, beans and nuts. Besides being used as an energy source, it also helps with growth, especially of muscles.[13]

The latter is important for weight loss, because as mentioned in the last post, weight loss will also consume muscle mass, not just fat mass. Increasing the protein amount in food in addition to strength training can effectively counteract this.[14]

Another effect of protein is its effect of reducing hunger.[15] Low-calorie diets can therefore benefit from a higher protein content by making them easier to adhere to.

Hunger

Aside from the energy composition of food, an important impeding effect for weight loss is hunger. Trying to simply ignore hunger is a lost cause. Sadly, hunger is incredibly complex and barely understood. It consists of a number of different and partly unrelated factors, and it is quite likely that the exact way those factors interact varies greatly between individuals. So what works for some or even most might not work for you or me.

The main chemical basis for hunger appear to be the hormones ghrelin, peptide YY, cholecystokinin and leptin. All of these interact, with some of them being affected by other hormones as well. For example, ghrelin is affected by both leptin and insulin.

Leptin has a number of other effects related to weight loss. For example, “[t]he decrease in energy expenditure with weight loss is caused by […] a decrease in leptin, which decreases the metabolic rate by acting in the brain,”[16] and it is also likely a main regulator of telling the body at what weight it should stabilize at,[17] a prime culprit for the infamous rebound effect. Most importantly, obese people can develop a leptin resistance, which can cause overeating,[18] as it is basically making them immune to satiety.

The problem is, though, that we barely understand how these hormones interact, and this makes it difficult to utilize hormonal effects to reduce hunger. While protein reduces hunger,[15] glycemic load or the glycemic index seem to have no effect on energy intake or satiety,[19] making a lot of dietary advice redundant.

Besides those hormonal causes for hunger, there are also physical causes. The body seems to know about two kinds of satiety in this case, intestinal and gastric satiety, with the primary signal being how full the intestines and stomach are.[20] This actually might be more important for food intake than nutrient content,[21] and would imply that larger volumes of food with low energy density lead to higher satiety.

A lower frequency of meals causes higher spikes in insulin, while a higher frequency causes a generally higher level of glucose in the blood, but these differences do not affect fat gain. A lower frequency of meals reduces hunger, though.[22]

On the other hand, eating slowly seems to have little to no effect on satiety.[23]

All of this boils down to some simple observations. A low energy density in food with higher protein levels eaten in only three meals a day helps with satiety, while the exact composition of the food or the exact times of those meals are mostly irrelevant. Additionally, obese people can have serious trouble knowing when they ate enough, and likely need to restrict the amount of food they eat based on external factors, not on what their body tells them. As the amount of food needed for weight loss depends solely on calories, this is a major application of various forms of calorie counting.

Calorie Consciousness: Calorie Counting For People With a Life

What we have learned so far is that to lose weight and fat, we need to stop eating too much, and that especially obese people have a naturally hard time knowing when that would be. Counting the calories consumed on a day and comparing that with a self-defined limit could help these people know when they should stop eating.

Possibly even more importantly, such a limit can also tell them when they can eat. Overweight people usually feel bad every time they eat something, because they constantly tell themselves that this is too much food and they really shouldn’t eat this. This self-deprecation can turn into a depression. But if they know how many calories they can eat based on their diet, and know how much calories their food has, they will be in the situation that they know that they can and should eat this now. This way, they can stop feeling bad about the food they eat, because they know they actually are not overeating, and that their body needs this food now.

Counting the calories you consume every day would solve all of this, but few people have the time nor interest to actually do that thoroughly. I’m not going to recommend that. Not only because it’s simply unrealistic to expect most people to do it, but also because it simply doesn’t work. Instead, I’m going to recommend something I call being calorie-conscious: You do not need to know the exact amounts of calories, but being conscious of rough quantities is extremely helpful.

Limits of Calorie Counting

In theory, counting calories is trivial. Most foods have calorie values printed on them, so it should be a simple matter of adding them up. Sadly, it’s not quite that simple. Calorie counts for foods are slightly inaccurate, and can be somewhat off especially for healthy, natural foods like vegetables and fruits. Also, we rarely consume the foods we buy completely. Putting fat into a pan to fry a piece of meat will not automatically make you eat all the fat you put in there. And then you will not eat all the food you make, because some of it will simply stick to the pots and pans.

Even worse, if you are like me and actually eat lunch at restaurants around your workplace, you will not even get calorie counts at all.

Counting calories is an inherently inaccurate, approximate process. You need to put in a lot of effort to get those counts, and if you really want to, there’s literature out there.[24] For the rest of us, a rough idea of calorie numbers is all we need, though.

Finding Calorie Sources

It is perfectly sufficient to have an approximate idea of the calories you consume a day, and to get this approximation, you do not need to have full calorie logbooks or whatever some people recommend.

When you decide to reduce your calorie intake, start by listing typical meals you eat, and do a full calorie count on them (don’t forget drinks). No worries, you need to do this only once. This list can give you a rough idea of the amount of calories you consume, but also where your major calorie sources are from. The latter allows you to efficiently pick those foods that provide the most calories to you and see if you can drop or replace them with something having less calories. This also works for typical meals at restaurants, even if you do not know the actual calorie values.

Every time you want to restrict your intake further, you can re-do this kind of rough estimate and check for further calorie sources. Remember to pick a calorie goal first, though. Let’s say you are aiming for a 2000 kcal diet. This means that you probably want to consume about 1000 kcal for your main meal, and then maybe 500 kcal for the two others. If one meal is above these calorie goals, see if you can cut it down. If a meal is below it—either increase its calorie value, or add some more calories to other meals! Remember you need calories. Just not too many of them.

As this is a process you only do once in a while, it’s not really a big effort, and it can help you understand the composition of your food better.

Typical calorie values for different foods, from simple ingredients to full meals at larger restaurant chains, can be found using various internet resources. Some examples:

Some people feel that a food log book helps them, that is, a log of what food they eat thorough the day. It is easy to forget all the little snacks you eat. The ideal solution here is to just not eat those snacks, but if you do, feel free to do a log book of the food you eat for a week so you can do a better job at approximating your calorie intake.

Choosing Food

The other important use for calories is choosing food. As mentioned, most foods these days have calorie counts written on the packaging. This gives a very important information when shopping, namely the calories per 100g value (or whatever it is in imperial countries). You can mostly ignore the “per serving” value, because the serving size is pretty much a fabrication completely unrelated to reality, but the calories per 100g value is extremely useful.

The lower this value is, the more of this food you can eat while consuming the same amount of energy. The more food you eat, the less hungry you are.[25]

Comparing this value between foods can be the most important factor for purchase decisions. If a great “diet version” of some food saves only 2 kcal per 100g, who cares? But if you notice that you could halve the calorie value of a meal just by switching the type of meat to something else you like, that is an important boost for you.

Make it a habit to always look at kcal/100g values, even if you are not comparing to other foods. This will teach you a lot about food and typical energy levels, helping you to better judge the value of food for your fat loss. In time, you will even get an intuitive understanding of the calorie values of various meals in restaurants.

Incidentally, healthy foods like vegetables often have low calorie values per mass, meaning with this method, you will almost automatically prefer healthier foods to get pretty large meals with low calorie counts.

Meal Composition

For the purpose of losing weight and fat, I could stop here. Consuming fewer calories than you expend is all that you need to do for that. But losing weight is not everything, we usually do that to live healthy, and there are more things to living healthy than just low weight.

It is easy to fall for the idea that you only need to change your diet until you lost enough fat. This is a prime factor for regaining all the weight you lost. When changing your food composition and meal types, try to aim for changes that you are willing to keep up forever. Once you have lost enough weight, you can eat a bit more again, but the general food composition shouldn’t change again.

Frequency

First of all, aim for three actual meals a day (at most five if you absolutely can’t sustain three). First of all this makes it easier to keep track of your calorie intake without constantly counting everything, as we tend to consume a lot of calories in those little snacks and can easily forget about them. Additionally, fewer meals reduce your feeling of hunger.[22] Also, do not skip a meal. Your body needs the calories to function, and you want to consume calories to keep weight loss at a slow but steady pace. And it does not particularly matter when on the day you have your meals, all three of them should be sensibly sized. Enjoy eating the food your body needs!

Do not eat any snacks in between those meals. You can drink water, tea and coffee (unsweetened, no milk) as much as you like. This will be difficult for a few days, as your body will be used to get food often, but your body will adapt and you will get used to it. If you absolutely need to eat something between the meals, have some low-calorie product prepared. Salads (without dressing), vegetables or yogurt work well here (make sure it doesn’t have added sugar).

Composition

No food (that is commonly sold) is so bad that you must under no circumstances eat it. While some food is more healthy than other, being constantly worried about the composition of your food is also not particularly good for you. Simply do not fuss too much about the composition of your food, and enjoy what you like to eat.[26] Still, having some ideas about good compositions of a meal are helpful.

Also, different kinds of meal compositions have different effects on appetite. One of the more impressive displays of this was mentioned in a side sentence in one study. The scientists had put subjects on an energy reduced (ER) intake diet and provided food for them, but found out that “the provided meals were more satiating than foods the subjects were used to and some subjects on the 10%ER reported themselves unable to finish all their provided food.”[27] These people consumed 10% less calories than they needed to maintain weight, and simply couldn’t eat all of it because the food composition was better than what they were used to.

The following are guidelines composed from a variety of sources.[28] [29] [30] [31] They are meant to give you a rough idea of what to aim for, not as a restrictive corset which suffocates you. Remember to enjoy your food and not to worry all the time about what you eat.

About half of any meal should consist of vegetables and fruits, ideally with more vegetables than fruits. Aim for at least 400g of vegetables and fruits a day. Vegetables here do not include potatoes, they’re covered below.
The other half of the meal should consist of grain products and proteins at about equal quantities. For grains prefer potatoes and whole grains, like brown rice, whole-wheat bread and whole-grain pasta. For proteins, aim for fish, poultry, beans and nuts. Guidelines recommend a total of no more than 300–600g of low-fat meat like poultry and 1–2 servings of fish per week, but considering the positive effect of proteins during weight loss, I’d not be too worried about consuming more meat than that.
In addition to this, go for about 1–2 servings of low-fat dairy products a day.
In general, aim for a high variety in foods and reduce sugar and salt contents.
You should drink about 1.5l of fluids a day. Avoid soft drinks and fruit drinks. Juice is also very high in calories, so try to stick to one small glass a day. Water, tea and coffee are great. Low-calorie soft drinks also work, artificial sweeteners are not particularly unhealthy.[32][33]

That’s it. Again, these are rough guidelines that should help you find meals that you like and enjoy eating. Do not hesitate to experiment and try new recipes.

Conclusions

Food provides us with energy from the three macro nutrients fat, carbohydrates, and proteins. None of them are in and by themselves unhealthy or bad for losing weight. They do provide calories, though, and your body can convert them all to fat tissue if you eat to much. These are the nutrients you need to cut down to lose fat.

Obese people can have a biological problem knowing when they ate enough. Being calorie-conscious will help you both knowing when you should not eat anymore, but also allow you to eat without feeling bad about it. Additionally, it will help you to understand food composition better and help you make decisions when buying food or ordering in a restaurant.

There are a number of simple guidelines which can help you to compose healthier meals. They are guidelines, though, not laws. The most important part of any diet is not the exact composition of food, but that it allows you to stick to it. If you change your diet according to these guidelines, try to do it not only for a short time, but as a general change in your life. The less you expect to change back, the less you will fall back into the bad habits that made you overweight in the first place.

In all of this, remember that every human is different. We know too little to have fully-generalized recommendations for everyone. Something that works for one person might not work for another. If something does not work for you (after trying earnestly!), change it.

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Saturday, July 7, 2012

Energy Intake: Food, Diets and Nutrition (Weight Series Part 3)