We have all heard about or experienced it. Yo-Yo dieting. Down some pounds, then up. Back and forth. A diet works for a while then stops or you fall off the program, just to bounce back to where you started or beyond. Conventional wisdom would have us believe this is bad behavior.

I would like to propose that, in a sense, this behavior is precisely what our bodies are designed to do. And, in fact, not only might this be normal and good for us, if done naturally it might be ideal for optimal health and longevity.

I am a yo-yo dieter and proud of it. My weight changes all the time and typically fluctuates 10-15 pounds a year. Here’s my last few years as an example:

Why do I yo-yo? Because that’s what I like to do and I believe it’s good for me…

Rethinking Weight Changes

My diet and weight changes all the time because I want to experience both energy surplus and energy deficit. I want to experience times of carbohydrate abundance and carbohydrate scarcity. I want my body to experience living off fat stores and cleaning things up. I want times of metabolic vigor (charging full steam ahead) and times of metabolic governing (throttling back, management, reservation and control). I think that my body does well with periodic doses and stretches of differing calorie and energy intake and it becomes more seasoned at each experience the more I practice. I don’t take things to an extreme either way (aside from some minor fasting or a birthday party here and there) and my weight fluctuation approach has enabled me to have times of indulgence and growth, times of challenge, discipline and retreat and, most importantly, learn a lot about my body and how I work.

A few important points to keep in mind:
1) I started from a pretty good metabolic place
2) I haven’t strayed too far in either direction
3) I don’t spend too long at my highest or lowest weights
4) I try to make my major fluctuations seasonal
5) I do this purposefully and thoughtfully

This yo-yo approach is consistent with my lifestyle approach and honors basic human physiology. Although I am not necessarily trying to recreate an ancestral biological environment, I do think there is wisdom and much to learn from looking at how prior and non metropolitan humans (and mammals in general) often change and adapt their energy intake and weight throughout the year. Life and nature is made up of balances and seem to work best when both sides ebb and flow. Stagnant and/or perpetual states usually do not thrive in the natural world. I think human metabolism is no different and giving the body a nice sway between comfort and compensation is honoring the body’s natural state.

Yo-Yo Dieting: An Evolutionary Perspective

Human biology, adaptation and nature
Humans are mammals. Mammals are warm blooded creatures that have evolved adaptations to the natural environment. To live with the seasons, constantly adapting and surviving. When it comes to our biology and the natural environment, it is important to remember humans are still very much wild animals.

Everything in our bodies and brains are hardwired for natural environmental input. Humans are innately designed to adapt and interact with two natural cycles: geothermal (hot/cold) and photo-sensory (light/dark). In a natural environment, humans experience day/night and hot/cold very directly. The entire foundation of our biology is designed around the ancient relationship we have with these cycles. When the sun comes up, our biology changes. When the sun goes down our biology changes. When it warms up, we change. When it cools down we change. Humans are in a constant dynamic relationship with the earth. Like other mammals, we adjust our habits, behavior and biology depending upon the environment and this changes throughout the year.

Here’s how it works for every other organism on the planet and should work in general for humans:

Let’s start in the spring, universally known as where life and growth begin. Animals and plants emerge from the cold winter to experience warming temperatures and days that are beginning to lengthen. This is natural feedback from the earth. As plants begin to grow and animals emerge, everyone has access to more food. The warmer temperatures and longer days signal our brains it is a time of abundance. This on the simplest level means eat and enjoy while the eating is good. As the days become warmer, longer and food becomes more plentiful our biology changes in concert with the season. These clues from nature tell the brain to make some amazing changes. We start to crave and eat more carbohydrate and sugars because they are available and in season. We slowly put back on some of the weight that was lost during the scarce winter and early spring.

During the summer months the body rages full steam ahead and life is good. Metabolism is blazing ahead, energy expenditure is high and hormones are flying about. Humans become the most fertile in the summer and fall which often leads to babies being born in the spring time (like most mammals). As life continues to go well the summer turns to fall and the days start to shorten and the temperature starts to decline. The body continues to make some adaptive physiological changes to help navigate the upcoming energy shortage. Signaled by the environmental clues, our brains down-regulate the cells in our body to alter the cell membrane structure and become more insensitive to energy. This means the body has excess energy floating around in the blood. What happens? What was getting used for activity, growth, reproduction now starts to get stored as fat. Why? Long days, warm weather and carbohydrates tell the brain to store energy because stingier months are right around the corner. When you have a seasonal, opportunistic, strategic and feast/famine biology, you better hold onto some energy extra for the days when it’s not available. The excess fat will provide insulation and fuel and the increased amount of sugar and polyunsaturated fats will lower the freezing temperature of the cells in your body. The body is fattening up and changing the composition of its cell membranes to prepare for cold and a period of less energy. The brain, taking clues from the environment, will make the body diabetic and fat to survive. Utterly amazing when you think about it but this process is no different than countless other animals living in the “real” world.

As the days then start to get shorter and colder our biology changes as well. We start to become more adapted to the cold, metabolism lowers and we settle into a nice maintenance and repair mode. Longer nights mean more sleep, rest, recovery and lower energy requirements. Due to the lack of abundant dietary energy and carbohydrate in particular, the body burns stored body energy very effectively and efficiently. We live off the spoils from the seasons of abundance. Hormones regulate themselves and the whole human biology regroups and simmers. The flame still burns and the pilot light doesn’t go out but it is a much different flame than in the long, warm days. As winter progresses our brain tells the body to become more sensitive to energy, we lose the excess weight and return to our biologic baseline for the emergence of spring. By living through a period of lower energy, cold and little to no sugar, we cure our own diabetes. Fully repaired, recovered and balanced, we now transition into warming and longer days and embark upon the next year of life.

The flowers start to grow and the cycle of life continues.

Humans, like all mammals, are designed to gain weight in the summer and fall and lose it in the winter. We are, in essence, genetic, natural and programmed “yo-yo” dieters. This is why I am a yo-yo dieter…

What can we learn from this framework?

Long days and warm temperatures signal abundance and tell the body to 1) thrive while it can and 2) store fat and prepare for cold and famine. This usually means carbohydrate cravings.

Shorter days and cold temperatures signal scarcity and tell the body to 1) manage output and 2) live off its resources because that’s all it can count on. This means burning body fat.

Thrive, build, flourish and live off the earth in the warm months. Moderate, recover, repair and live off “you” in the cold months.

It is OK (I propose it’s a good thing) to blaze full steam ahead for a few months a year. Stay up late, run around, eat like a teenager and have fun. Live life to the fullest. Get out in the sun, exercise, run, walk, swim, hike, play, vacation, etc. Enjoy the summer.

Use the winter to regroup. Let your body recover. Go to bed early, sleep as much as possible. Eliminate fruits and sugar. Exercise less. Get outside and experience the cold but don’t overdo it. Let burned out adrenal glands take it easy for a while. Eat simply, fast every once in a while and let yourself live off your fat stores. It can be a tremendously freeing experience to not be controlled by hunger and food. Let the body transition slowly, use the seasons as your guide. As it gets darker and cooler, phase out summer behaviors and phase in winter behaviors. It’s not a science, go by feel and do what feels right. We all have within us the innate sense of what the body needs. We just need to reconnect to that pathway. Living by the seasons and becoming a yo-yo dieter is a good way to do that.

The inherent problem is that we are trapped in a domesticated world. Under normal circumstances, when we receive accurate environmental sensory input we have natural homeostatic processing and rhythm. However, when we are bombarded with environmental stimuli that is incongruent to our genetics we get a biological mismatch. This creates many of the problems we see in the modern world. I think this the THE main reason we have modern disease. Nearly every aspect of the modern world is incongruent to human genes and biology.

As an example, humans have a very dynamic metabolism and biology. We are adapted to inconsistent energy input and output. We did not have 2000 calories of food available to us every single day of the year. Certainly energy intake was less during the winter than summer but it also varied from day to day and week to week. We are hardwired to have ups and downs of energy and weight almost on a daily or weekly basis and certainly on a seasonal basis.

A prime example would be to look at temperature and seasonality. With the exception of the poles and equator, there are typically large seasonal variations in temperature. This means large variations in type and availability of food and human weight will fluctuate via the environmental changes. This is normal metabolic behavior. Static, regular food availability is new to humans, particularly the way that the United States and other developed countries live.

Being guaranteed your next meal and a constant supply of energy isn’t necessarily a bad thing- I simply want to offer the idea that it’s new to our ancestral DNA, may not allow us to take advantage of many of the biological programs that thrive on energy fluctuation and may be part of the problem we see in health problems across much of the population. Through thoughtful and practical behavior adaptations I think we can not only honor our physiology but take advantage of the complex systems we’ve been developing over hundreds of thousands of generations. Seasonal eating and weight fluctuation, when paired with other traditional seasonal human behaviors, just might be one of the best tools available in reconnecting to true health and vitality.

The Bare 5 Bottom Line on Yo-Yo Dieting:
1. Fluctuating periods of under eating and over eating is very normal for the human species.
2. Our bodies are designed to be able to handle this and actually expect it.
3. Depending upon season, light, temperature, activity level and food availability our bodies change weight to adapt.
4. If you go through a period of energy deprivation, the body expects a period of energy surplus and vise versa.
5. It is in this ebb and flow of energy intake that the body stays balanced on a daily, weekly, monthly, seasonally and yearly basis.

Thanks for reading, have a great day!