At the checkout of any supermarket, we see the headlines of a variety of magazines telling us how to shed the pounds. The advice ranges from:
* keto
* paleo
* vegan
* intermittent fasting
when it comes to nutritional approaches and in terms of exercise our options include:
* HIIT (high intensity interval training)
* traditional cardio (running, swimming, biking etc)
* resistance training (bodybuilding, powerlifting, Olympic lifting etc)
These headlines are accompanied by someone holding up their old jeans, usually two or three times larger, and made more compelling when it's a celebrity.
But do the best results go to those that cut out the most sugar, track their macros and do the most WODs in the least time?
A new book on metabolism, Burn, challenges some of the conventionally held beliefs when it comes to how to successfully achieve weight loss and health.
Three of the takeaways from this book include:
1. Limits on Calories Due to Exercise
Many people will agree that weight loss starts in the kitchen. But at the same time, when they want to drop the last few pounds, or get stage ready in the case of a bodybuilder, there will be an increase in the volume and or intensity of exercise.
For example, figure competitors will add in an extra cardio session in the morning, usually in a fasted state, to burn a few extra calories.
But the body has a variety of systems to manage including the reproductive, nervous, cardiovascular, respiratory, endocrine, digestive, urinary and lymphatic. Those paying attention will notice I left out the skeletal and muscular systems, which may be considered lower order than the previous list.
The body has a built in governor which limits how many calories we burn as a result of exercise. Think of a golf cart going down a steep hill. The golf cart is limited as to how fast it will descend the hill as a safety feature. In a similar fashion, the body limits how many calories we burn as a result of our efforts in the gym or our run, in order to preserve enough energy for the brain, reproduction and other jobs deemed for important for survival than six packs and biceps.
2. Evolutionary Constraints Influenced Our Metabolism
If you've ever done some pruning in the yard or garden, there are things we can do which influence how a plant grows. For example, at the top of a plant is something called an apical meristem. When this is pruned it limits vertical growth of the plant, and instead we see lateral growth. The lateral meristems are stimulated and we see the plant become bushier rather than taller.
Over time, our own metabolism has evolved due to a variety of constraints and changes in the environment. For example, grazers such as cows, have long digestive tracts which negatively impact the development of more advanced nervous systems. Humans have smaller digestive systems and benefitted from more highly developed brains.
There are similar explanations for the digestive enzymes in our bodies i.e. amylase, lactase, pepsin, the type of teeth we developed (flat for mulching and sharp for tearing) and the fact we are upright, bipedal animals with opposable thumbs.
Evolution is almost like an accountant's ledger. When one feature or trait is expressed, such as a more highly evolved brain, this could be at the expense of another feature which is suppressed, such a long digestive tract. The brain is a more energetically expensive organ than the GI tract, and is part of the reason our metabolisms are higher than cows.
3. All Diets Work
To summarize this point in one sentence would be to say that all diets work because they create a caloric deficit.
Vegans lose weight because it's hard to eat too much fiber and because fruits and vegetables contain a lot of water.
Keto diets work because we eat fewer carbs and then deplete our stores of glycogen in the muscle and liver. In order to metabolize this glycogen requires water and so we drop pounds (mostly water weight) when we cut out cereal and bagels.
Intermittent fasting works because we limit the hours of the day that we eat. Less time for eating means fewer calories consumed.
Ultimately the best diet would be the one that:
* doesn't limit nutrients
* is healthy
* creates a caloric deficit
* and is sustainable
Going forward if your goal is to be lean remember to not over-do-it when it comes to exercise. More is not better and excessive efforts many not yield the desired, and expected, burn of calories. Recognize when other systems of the body are in higher demand, our metabolism may be adjusted accordingly. And lastly, the most important thing you can do nutritionally is eat a little bit less. Many approaches are designed to achieve this and the best one is the one that you enjoy and follow most easily.