In my most recent quest for weight loss I tested out a low fat diet in order to achieve fat loss without sacrificing muscle, despite all of the current guidelines which suggest low carb diets are the way forward. It’s based on simple science…
Our body uses 3 fuel systems:
Aerobic System – uses oxygen, fat and carbohydrate to produce energy. Preferred for lower intensity activities from sleeping all the way to jogging or other sustainable activities which we can do for long periods. This is the one that we use most, if not all of the time.
Lactate System – uses carbohydrates to produce energy. This system kicks in when we up the intensity to a level where the body can’t supply enough oxygen to use the aerobic system, at which point a different chemical reaction occurs using only carbohydrates. It’s better for high intensity actives which are only sustainable for a few minutes or less. This is usually reserved for people who carry out physical activity.
Creatine Phosphate System – uses the chemical creatine phosphate to produce fast energy. This system is the most superior in terms of intensity however the output at this high level can only be sustained for around 10 seconds before the intensity is forced to drop and the lactate system takes over. This is almost certainly reserved for people who carry out intense physical activity or explosive movements.
The important bit here is that the aerobic system is the only one which burns fat. BUT…and it’s a big but, this system only burns all 3 fuels together, fat, oxygen and carbohydrates. If any of those are not present, the chemical reaction won’t take place.
What does this mean? It means that if we don’t have carbs in our system we can’t burn fat. So what happens if we remove carbs from our diet? Well, we need to get the carbs from somewhere because fat on it’s own is useless. So the body becomes “catabolic”. This is a state where the body breaks itself down, more specifically, the muscle tissues, in order to convert the proteins which make up the muscle, into carbs so that they can be used to produce energy. This loss of muscle mass can help to explain why the weight loss results from low carb diets are so dramatic as muscle is more dense than fat.
Here’s an image to break up the monotony.
But what if we don’t want to lose muscle? Then we need to ensure that our diet contains sufficient carbohydrates and protein. To reiterate what I’ve said in previous articles, there are 3 sources of energy; fat, carbs and protein, where fat and carbs are used for energy and protein is primarily used for growth and repair. Only when we run out of carbs do we use the protein for energy by converting it into carbs. We can’t use protein itself as a source of energy, as highlighted in my description of the three energy systems above.
But what happens if we remove fat from our diet? Well technically, without fat, we can’t use the aerobic system. That basically rules out life. We simply can’t survive without it. We’re lucky though, because even if I was to completely remove fat from my diet for an entire week or more, I’d still have plenty of fat in my body to provide sufficient fuel. If we have any fat under our skin whatsoever, it’s fair to say that we’re not in trouble of running out any time soon. We also have fat stored in our bloodstream, our muscles and our liver. Anytime we eat more fuel than we use, it gets converted into fat and stored in one of the aforementioned places.
So logically, if we maintain a high protein and carb intake but limit the fat intake, we’ll need to take fat from our reserves i.e. our body fat. This SHOULD result in fat loss but not muscle loss. Does it work? Yes, as many bodybuilders will tell you, but it’s not that simple. I’ll throw some figures into the equation to make this easier to explain.
Using me as an example, to maintain weight I require around 2400 calories per day (removing any exercise sessions from the equation). According to myfitnesspal, my breakdown should be around 50% carbs, 20% fat and 30% protein. So that’s 1200 calories form carbs, 480 from protein and 720 from protein. To remove the fat intake completely from my diet I’d need to consume the remaining 1920 (1200 + 720) calories from carbs and protein. This would then leave me with a daily deficit of 480 calories which my body should extract from its fat stores.
Given that there are 9 calories in every gram of fat, this suggests I’d lose around 53 grams of fat each day (480/9) or 371grams per week, which incidentally is less than 1lb.
So why did I lose so much weight when I did the low fat diet? It’s because eating 1920 calories of low fat food is damn near impossible. My diet consisted the following:
5am: rice crispies and skimmed milk
9am: Low fat meat such as tuna, turkey or chicken
12pm: Sushi and more low fat meat
3pm: more low fat meat
6pm: even more low fat meat
9pm: 1 sweet potato, some low fat meat and steamed vegetables
This totalled to around 1400 calories per day but I couldn’t manage to eat any more than this without going for sweet treats such as entire packets of wine gums or sugar based treats. Remember-I was allowing myself no fat so things like chocolate, pastry, bread etc. are all ruled out!
When factoring in 5 hours of exercise per week on top of this I was creating a weekly deficit of over 10,000 calories per week, which in terms of fat, is more than a kilo per week, but as I’ve been trying to explain, my sub-optimal carb and protein intake meant that I lost muscle too, not just fat.
There’s a theme!
On the above diet I constantly felt full. Even eating that much was a challenge, hence the 1000 calorie deficit per day. Here lies the theme among most successful weight-loss diets. They make you unable to eat enough calories to gain weight. As soon as we start stipulating rules around what we eat, assuming they are sensible rules, the likelihood of overeating deteriorates. There are no magic foods which make you lose weight or which slow down digestion so that you don’t gain weight. The most successful diets in one way or another reduce the likelihood of you consuming more than your necessary calories, and as a result you lose weight.
Let’s observe a few diets and see how they may reduce our calorie intake.
Low Carb Diets
Vast amounts of our calories come from energy heavy carbohydrate sources such as pasta, potato, bread and rice. Take these out of the equation and the total amount of calories you consume drops drastically.
Low Fat Diets
Gram for gram, fat contains over twice as many calories as protein and carbohydrates so when we reduce the fat intake, we drastically reduce the total amount of calories consumed. Also, carbs on their own tend to be a bit gross. A jacket potato without butter or cheese can get outta here, as can most other carby foods if we take away the fat.
The Dinner Diet (only having one meal per day)
Surprise, surprise, if we remove breakfast and lunch from the equation and only have one large meal per day, we don’t consume as many calories as we would if we had three meals per day. Trying to consume enough food to gain weight in one meal is damn near impossible.
The Hay Diet (separating carbs, fats and proteins into separate meals)
If we avoid mixing food groups within a meal it makes it extremely difficult to consume vast amounts of calories. Just protein on it’s own isn’t very appealing so we’re unlikely to binge on it. Carbs without fat tend not to be very tasty, consequently we won’t eat lots of them on their own. Fats without carbs tend not to be very nice either so we tend not to eat large volumes of food on this diet.
So What’s the Secret to Success?
I can go on and list all of the various diets but it’s not the diets that are important. It’s the effect they have on your total calorie consumption that makes the difference. The one thing that all of these diets have in common is the fact that if you adhere to the rules, you won’t consume very many calories, which will over time result in weight loss. I often hear people talking about diets, discussing which ones work and which ones fail. The truth is, diets don’t fail…PEOPLE fail. All diets are based on simple logic and if you have the mental strength to stick to the rules you’ll lose weight. Blaming the diet is an easy excuse for people who don’t have the staying power to stick to the diet. I’ve said it many times, but once your health becomes a priority, you’ll make your diet work. Until then you should just accept that you have other priorities and focus on them instead. So, in a word, the secret is to change the way you think about food. Understand that food is a means of survival, and that you don’t need to constantly feel full, in order to stay alive.
There are other factors which help to explain our desire for good tasting foods and why many of us find it difficult to control what we eat and I discuss these in more detail in my book so if you’re “hungry” for more info (excuse the pun) you should download it now!