Our sedentary lifestyle is making us weak – and fat. But there are ways to beat the sitting bulge, says Dr Michael Greger.
How Not To Diet (Macmillan) is a treasure trove of science-based data and dietary research, translated into accessible, do-able advice. The American physician and nutrition expert breaks down a variety of approaches to weight loss, including how to structure a low-sugar, low-fat diet packed with anti-inflammatory foods. He then goes beyond food to explore the many other weight-loss accelerators available to us.
One of these chapters focuses on what’s been dubbed the “sitting disease” – the health risks associated with excessive sitting, at our work desks and in front of our computers, phones and TVs. In the following extract, Greger finds out what protects some people from the fat-gaining effects of over-eating and a sedentary lifestyle – and how everyone can benefit from an activity called NEAT…
Hold on. Someone ate 56,000 extra calories and gained less than a single pound of body fat? There’s a law in physics that basically says calories can’t just disappear, so what happened? Let’s look at the energy balance equation again:
Body fat = food + beverages
– metabolism – exercise
– other movement
The exercise level for the study subjects was fixed at a steady, low amount, and it turned out their metabolisms didn’t change much. So the only way caloric intake could shoot up without depositing as body fat would be if “other movement” shot up as well. And that’s what happened. The secret to eating in excess of 50,000 calories without gaining weight is NEAT: non-exercise activity thermogenesis.
NEAT is the heat given off by our regular activities of daily living, such as standing, moving and fidgeting. On average, fewer than 400 of those extra 1000 calories consumed each day of the study ended up being stored as fat. The bulk was burned off, particularly from a spontaneous increase in movement. One participant inadvertently started moving so much that an extra 692 calories burned off in a day. That’s like spending a quarter of your waking hours in motion.
You’d think overfeeding might lead to the opposite: inactivity. I imagine someone crashed on the couch rubbing their swollen belly. But no – when people are fed 1000 extra calories a day, a strange thing happens. They spontaneously start to move more out of some instinctual drive. This could be in the form of fidgeting or gesticulations, a restlessness leading to frequent standing or pacing, using up as many as hundreds of extra calories on average over the course of a day. Basically, NEAT is the sum of calories burned by everything we do that is not sleeping, eating, or sports-like exercise.
So the primary reason some people gain more weight than others despite eating the same amount of food is that they go weak in the NEAT. Easy gainers just don’t intuitively start moving more to compensate for the extra calories. Indeed, a NEAT deficit has been identified in obesity. Studies show obese individuals tend to remain seated for about two and a half hours longer each day than the average, inactive yet lean, shoestring couch potato. Normal-weight individuals just tend to get up and move around more.
After fitting “sedentary” people with sensors that tracked their posture and movement, researchers were surprised to find they in fact were walking the equivalent of seven miles a day (11.2km). That distance was just split up into dozens of stints lasting a few minutes at a time simply ambling around throughout the day. Remarkably, those small moments of movement can add up to more than 2000 calories a week, which just so happens to be what those overfed study subjects started burning up and about what you’d get from the hour-a-day exercise recommended for weight loss.
Just by subtly moving around more, your body can drain off as many calories as pounding it out an hour a day at the gym. Remember those extra 692 calories a day burned off by the study subject who had inadvertently started moving more? That’s more than you might burn rock climbing for an hour. Given its demonstrated power, if our bodies aren’t going to move more unconsciously, then maybe we should make a conscious effort to accrete some NEAT.
Staying one move ahead
You don’t have to go full horse-and-buggy to enjoy the benefits of non-exercise activity thermogenesis. NEAT means taking the stairs instead of the escalator and parking at the far end of the lot. It means singing, laughing, cleaning and doing yard work – any activity that creates muscular contractions. Cooking dinner burns five to 10 times more calories than sitting in front of the TV.
Imagine two scenarios of modern life: an office worker drives to work, sits all day at their desk, drives home, and then sits all evening watching television or surfing the internet. If they had gotten home at 5pm and went to bed at 11pm, those six hours of leisure time probably wouldn’t expend more than 50 calories, even if they double-thumbed the remote control. What if instead, when our hypothetical office worker got home, they started raking leaves or vacuuming? They would have burned about 10 times more calories that same evening and around 20 times more if they more actively commuted, like biking rather than driving to work.
Stand to lose
What about standing versus sitting for weight loss? Standing burns three times more calories per minute than sitting. Even if you’re standing still, your postural muscles are tensed and stretched to fight gravity, so anything you usually do while sitting, try doing while standing, like watching TV or reading the newspaper. A sure sign that I’m speaking at a lifestyle medicine conference versus a more traditional medical event is how many more audience members are standing along the back of the lecture hall.
A standing desk can be as simple as a crate on a table you can use when you pay bills or watch cat videos on your computer. Prolonged standing on a hard floor can be hard on our feet, but using cushioned insoles in our shoes or standing on an “anti-fatigue” mat (or maybe a thick or doubled-over yoga mat) has been shown to help relieve discomfort. Another potential downside of prolonged standing is increased risk of developing varicose veins, a cosmetic concern hopefully offset by the decreased risk of obesity and premature death.
There are “sit-stand desks” available now that are height-adjustable so you can alternate between sitting and standing. In the short term, they were found to reduce sitting time at work on average by 100 minutes per workday, but after three months, people appeared to tire of them and only sat about an hour less a day. Those using sit-stand workstations were also found to compensate a bit at home by sitting down more in their off hours.
Even without compensation, though, standing for six hours a day rather than sitting may only net about a 50-calorie deficit daily. Walking at a treadmill desk, on the other hand, could wipe out more than 700 calories a day. Just moving at a snail’s pace at about one mile per hour, people burn an extra two calories a minute over sitting. That means you could erase more than 100 extra calories an hour while you work or 200 extra calories at 3mph. (My treadmill desk is currently set at 1.8mph, or 2.9kmh.) If you work 250 days a year and stroll while you work for even just half the workday, you could theoretically burn off 30 pounds [13.6kg] of fat a year if your body didn’t otherwise compensate for the 100,000 annual calorie deficit. No wonder obesity researchers have called for a “moratorium on the chair”.
Does productivity suffer using a standing or walking desk? With the exception of high-precision mouse tasks, work performance in general appears to be unaffected, but one study of transcriptionists on treadmill desks found their speed slowed by 16%, though their accuracy was unchanged.
While I’m a big fan of treadmill desks, I’ll admit they can be expensive and noisy. Even if the motor is quiet, the footfalls may be distracting to co-workers. (When I’m on the phone, interviewers sometimes ask me what that “thumping” is.) Stepping devices, also known as exercise steppers, are a smaller, cheaper, quieter and more convenient alternative. They have two pedals you stand on, allowing you to simulate walking up stairs. Steppers appear to burn even more calories in an office setting than walking, and you can simply slide them under a desk when not in use.
The object of the exercise
Walking briskly just 15 minutes a day is associated with a life span gain of about two years, for example, and an hour a day may give us four more years on this earth.
While the data on exercise for weight loss are relatively weak, the evidence supporting the overall health benefits of physical activity is overwhelming. For example, 40 minutes a day, four days a week, can improve erectile function in men. Being more fit can mean having more fun, all the while reducing risk of breast cancer, colon cancer, diabetes, gallstones, hypertension, heart disease and stroke. Exercise can also help minimise the bone loss that can accompany weight loss.
A single exercise session can improve insulin sensitivity for up to 17 hours and may be used to treat pre-diabetes as effectively as medications. Exercise is medicine. Researchers at Harvard and Stanford found that exercise may work as well as drugs for coronary heart disease patients and even better than some medicines for stroke. They suggested that drug companies should perhaps be required to compare any new chronic disease drugs head-to-head against exercise, as “patients deserve to understand the relative impact that physical activity might have on their condition.”
Significant decrements in artery function can be detected within three hours of sitting, while three hours of standing, even while motionless, does not produce the same effect. Part of the reason blood flow can be staunched nearly 40% by prolonged sitting is the 90° angle in our knees that kinks our blood vessels. When that’s straightened out by standing, our arteries remain fully functional.
If standing or dynamic workstations are not an option, taking five-minute walking breaks every hour can prevent the stiffening of the arteries that comes with prolonged sitting. Frequent trips to the watercooler (and then subsequently to the restroom) or taking out the trash during commercial breaks can maintain full artery function.
What are your options if you really can’t walk away from your workstation? Exercising your legs for 45 minutes before sitting down can preserve artery function – another advantage to an active commute. Researchers concluded that “people should be encouraged to engage in aerobic leg exercise before sitting for extended periods of time and, if this is not possible, sitting should be replaced by standing.”
Just standing intermittently for a few minutes an hour does not appear sufficient to counteract the adverse effects of sitting, and neither does a few minutes of pedalling under your desk with one of those sit-cycle gadgets. Constant standing works, though, as presumably would constant pedalling, an example of “dynamic sitting”. You may have noticed people in an office sitting on large rubber stability balls. That does activate trunk muscles in your core, but it’s been found to cause more low-back discomfort and spinal shrinkage, likely due to the absence of a backrest.
What about a fidget chair that allows for a degree of side-to-side lateral movement of your hips? Unfortunately, people tend to move so little while seated in them that they only burn about 13 more calories an hour compared to sitting in a regular chair. A cheaper way to burn comparable calories while sitting is the use of a fidget bar, a device referred to in the medical literature as an “under-the-table leg-movement apparatus”. It’s sort of like a balance beam that hangs under your desk that you can put your feet on to fiddle around, burning up an extra 22 calories an hour. Either fidgety approach could easily add up to burning 100 calories a day.
Does seated fidgeting protect our arteries, though? Researchers had people intermittently fidget just one leg for one minute out of every five, while keeping their other leg still. While artery function in the resting leg dropped, that of the restless leg experienced a pronounced improvement. This helps explain why frequent fidgeting appears to neutralise the mortality risk of prolonged sitting. What I liked most about the one-leg fidget study was that the researchers didn’t rely on any fancy gizmos. They simply had people tap their heel by bouncing their knee at their own natural cadence, something we can all try to remember to do. Just try not to annoy the person you’re sitting beside on the airplane or at the movies.