In my leptin series a few weeks ago, I hashed out how dietary choices direct leptin levels – as well as leptin sensitivity and leptin resistance. But there’s more to leptin processing than just the food we eat (or don’t eat). As it so happens, the environment in which we live – and the good or bad “stress” we experience in it – can have an overriding impact on leptin production. Researchers at Ohio State University injected a group of mice with cancer cells and followed their progress after dividing them into two groups. One lived in a larger and “enriched” community environment with various toys, hiding areas and exercise wheels. The other group lived in groups a quarter of the size in standard lab cages. What the scientists found might leave you scrutinizing your living quarters – or at least your social calendar.

The mice that lived in the enriched environment showed “reduced tumor growth and increased remission.” In fact, the tumors in the “enriched” mice were half the size of the standard cage group after only three weeks in the stimulating environment. After six weeks, the tumors of the “enriched” mice were one fifth the size. Furthermore, the researchers could see no tumors at all in a fifth of the enriched environment group at the end of those six weeks.

The enriched environment, the researchers discovered, “upregulated” the BDNF gene (hypothalamic brain-derived neurotrophic factor), which helps regulate appetite and energy. Mice raised in standard cages didn’t show as much BDNF activity as their enriched environment counterparts. The researchers then found that the “enriched” mice also showed “downregulation of leptin production”. The enriched environment, they determined through further testing, activated the BDNF/leptin axis, which then resulted in tumor regression for the enriched mice. When the researchers studied a third group of mice that couldn’t naturally produce leptin and then administered leptin to the group, their tumors grew substantially larger than a control group given saline.

But wait, there’s more. It’s a lesson crucial for living the healthiest Primal life possible. The physical activity of the mice in the enriched environment wasn’t what made the difference. In fact, when the control mice were allowed to run in a wheel, their corticosterone levels (stress hormone) dropped below the consistently higher levels seen in the enriched environment mice. The researchers attribute the discrepancy to “good stress” – the healthy challenge – of enhanced social interaction and intellectual stimulation in the enriched environment as opposed to the pure physical exercise allowed to the controls.

That’s right: it appears that the good stress of positive social and intellectual challenge can inhibit leptin production and associated cancer growth. You can tick off all the more “concrete” tasks of a healthy lifestyle (e.g. diet, exercise), but in the end you need to have a life too – with some constructive, character-building stress.

So often, we get overwhelmed by the responsibilities of our lives. We attack the day with task-orientation and then lament feeling bogged down by the succession of endless chores. Although few of us can completely clear our slates for the week, eventually, the to-do list can morph in an ongoing attitude. We feel overrun by “bad stress.” Yet, maybe it’s more a question of balance. We put off meaningful investment in ourselves as well as our relationships and family time. We tell ourselves we can live off reserves for now – the memories of previous experiences, the benefits of old adventures – while we meet other, more pressing obligations. I dare say that our psychological selves run down just as our physical selves do. Reserves don’t last indefinitely. The spirit, as well as the body, needs continual sustenance.

It’s worth asking, how enriched is your environment right now? Do you do a job or volunteer work that’s fulfilling and/or pleasantly challenging? Are you engaged in hobbies that call on your creativity? Do you take in events or activities that move you in some way – whether it’s a ruckus-rousing football game or a suspenseful book? Do you go the extra mile in your relationships and family to make some fun and adventure? When was the last time you felt like you’d really learned something? Grown from something? Cultivating genuine happiness isn’t a selfish endeavor. Investing in your personal development – even in the midst of a busy, responsibility-filled life – isn’t an egotistical indulgence. If we can feed the mind (remember law #10!) and spirit, we bring more – more energy, more inspiration, more motivation – to the daily tasks of life. Greeting them in a renewed, even changed frame of mind, we might see them differently. Good stress helps us balance out and even diffuse the bad stress of life. We’re happier – and healthier – as a result.

On that note, Grokkers, go forth, and relish your weekend! Grab it with both hands and run like mad. Make a memorable experience –and maybe even a great story – out of it. Does this have you thinking – stirring – planning? Share the love in our comment section before you bust out, and thanks for reading today.

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