After lunch one day, I swung by my colleague's desk to say hi. I found her munching away a bag of trail mix - the nutty mixture of roasted nuts, cereal, and chocolate pieces. She told me during our chat that she was trying to lose weight but was putting on weight instead. Finally, she told me, looking rather solemn, that this was because she was in starvation mode. I looked at the bag of trail mix. It has over 1,000 calories worth of food in that little bag. So starvation mode was clearly not the reason that she was gaining weight. But was I brave enough to tell her?
According to popular opinion, the term "starvation mode" implies that if you restrict calories too much for too long, your body will fight back and preserve what little calories it receives - as fat. But is this rooted in science?
Weight loss works on the energy balance equation. If you eat more calories than you burn, you store the extra calories as fat. If you eat fewer calories than you burn, you lose weight. If you eat the same amount your body needs, you maintain your current weight.
It's not so simple in practicality. Your body will adapt to the changes in your calorie intake; however, not as you would imagine.
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Let's take an extreme example; actual starvation. The Minnesota Starvation Experiment chronicles how in November 1944, a group of conscientious objectors to WW2 agreed to participate in a semi-starvation study to understand better how to refeed and rehabilitate American soldiers when they came back from war. During the 6-month semi-starvation period of this study, these men became too weak to open doors, highly irritable, food-obsessed, had muscle soreness, decreased tolerance for the cold, reduced coordination ringing in their ears, and their sex drive plummeted. Their bodies fought hard for survival. And yes, they did not gain weight.
Fortunately, most of us will never have to experience this dramatic loss of food. Most of us are simply looking to feel better and like what we see in the mirror. However, it's still hard to calculate our metabolism despite the available calorie and activity trackers. Shouldn't it be easy? Let me explain why not.
Based on population averages, calorie-tracking apps tell us how many calories we need to eat in a day to lose weight. However, these apps calculate metabolism based on mathematical formulas and not for the unique metabolism of the user. The only way to truly understand how many calories a person burns in a day is to use a hermetically sealed metabolic chamber, and I'm going to bet you've never hung out in one of these before. However, even if you were aware of how many calories your body burned throughout the day, that number isn't static and can easily change from day to day or over the years. Your daily metabolic burn is a moving target.
For example, according to a research study aptly titled "Fifty Shades of Brown", short-term cold exposure may help people with more brown fat burn 15 per cent more calories than those who do not expose themselves to uncomfortably low temperatures. That's fantastic for people in Nordic countries, but no calorie tracker on earth could be that astute to consider that. Your metabolism can also change with sleep patterns. Even after one night of poor sleep, your metabolic burn can reduce 5-20%, which is the difference of 200-500 kcal. A woman's cycle also impacts the number of calories her body burns during various times of the month. And, we age, we lose muscle mass, and that reduction (called sarcopenia) results in a lowered daily metabolic rate.
To add insult to injury, if someone has been dieting for a while, they will stop losing weight at the same rate and, eventually, stop altogether. This is because smaller bodies don't require as much energy to move around; therefore, they need less fuel. At this point, the dieter has a choice - to see results, they must reduce their calorie intake even further to match the new energy balance. An article entitled "Adaptive Thermogenesis in Humans", found in the International Journal of Obesity, points out that people who maintain a 10% (or greater) reduction in body fat experience a 20-25% decline in their 24-hour energy expenditure. According to the authors, this means formerly obese individuals require approximately 300-400 fewer calories to maintain the same body size as someone who has never been obese. And that's not just true for individuals with obesity. Folks who are looking to obtain a certain level of lean for aesthetic or sporting purposes find their bodies will fight back, making it not only physically taxing but mentally and emotionally taxing as well.
When you start drastically altering your energy balance, your body switches on its survival switch and may increase your hunger, appetite, and satiety hormones to rebalance the equation. This means we will be less satisfied with the food we eat and feel hungrier as a result.
And finally, as I alluded to in my story about my colleague and her trail mix, "eating too little" is a highly subjective personal point of view. Are they referring to "too little food" as less than what they usually eat or less than what they feel they should eat? Are they chronically hungry eating the way they are? And how long have they been eating "too little" - one day, one week, or six months? All of this matters; however, the answer is based on perception.
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Ultimately, the first step in achieving healthy, sustainable weight loss is to understand that if we aren't losing weight, there is a discrepancy in our perception of how much we are eating versus moving around. As a short-term solution, you may want to use a calorie counter or food diary to bring awareness back to how much you are consuming, understanding that it won't show you the complete picture. However, once you know—approximately-- how much you're eating, you can bring mindfulness back into your meals and only eat what satisfies you.