"My [insert other party] can eat whatever they want and they just don't put on weight! All I need to do is look at [insert arbitrary "naughty" food] and my weight goes up."
If there's one thing that any dietitian / nutritionist / coach will hear more than any other when it comes to weight loss, it's this. You may have even said it yourself, and if you haven't I'd wager you've at least heard someone say it before. Think about it - you go out to dinner with a group of people, and that one person who seems to stay perpetually lean throws back a whole pizza, burger(s), dessert(s), whatever. And this isn't an isolated incident - this seems to happen every time you go out, and it blows the collective mind of all who witness it. It's a completely understandable position to take; we often consider the monetary or lifestyle investment required for weight loss, but the emotional investment often trumps everything else. If it seems as though something we desire comes easily to those who apparently don't even try - all while we pour in effort for seemingly no reward - confusion and frustration often reign.
The reality is though, that there's a multitude of variables that account for and explain these apparent medical curiosities. And more importantly than that, there is one very special reason why you shouldn't care.
First though let's take a brief look at some of the inter-individual differences that can explain what is going on here. Perhaps the most obvious (and commonly cited) differences stem from variations in resting metabolic rate, and total exercise as part of their lifestyle.
The former is influenced by a host of factors such as age, gender, height, weight etc., and the latter is for the most part dictated by the will of the individual. Interestingly though, and perhaps even counter-intuitively, these are (in most cases) not the major variables at play.
1) Different levels of NEAT, or Non-Exercise Activity Thermogenesis.
If you're an avid follower of nutrition and exercise science, you'll be well aware of the contribution that NEAT makes to daily energy expenditure. For those of you who aren't familiar with the term, NEAT is essentially any and all movement that is not classified as formal exercise. That includes incidental moving around, housework, fidgeting, maintaining your posture etc. It may seem like a soft explanation, but in fact NEAT represents perhaps the most important inter-individual difference with respect to weight and weight balance over any period of time - so much so that the topic deserves its own article.
Very briefly though, what we used to assume were inherent differences between "fast" and "slow" metabolic rates can actually be explained by differences in NEAT . Those that naturally tend toward lower bodyweight have a much higher level of NEAT than those who do not. Interestingly, NEAT levels are also quite sensitive to changes in weight/calorie intake; when comparing individuals who have lost weight to other individuals at the same (new) bodyweight who have not lost weight, there is a significant reduction in total NEAT spend, accounting for as much as 350+ calories per day . This effect even seems to persist if the weight loss has been maintained for a year or more.
2) Difference in satiety/appetite, and caloric auto-regulation.
To put it more simply: "[x] can eat whatever they want and not gain weight" is not the same as "x can eat whatever I want and not gain weight". When it comes to weight loss, total energy balance is the single-most important variable over any given period of time. There's a tendency to view daily energy intake in a sort of vacuum, but total energy intake can actually be viewed as a weekly or even monthly balance. And herein lies the critical point - unless you're monitoring somebody 24/7, you can't know the sum total of all that they're consuming.
It might be seen that an individual eats a large quantity of energy-dense foods in a given sitting, but what may not be seen is the auto-regulated reduction in intake in the day(s) following this, which over time tend to even everything out. Indeed, individual variability in appetite regulation (genetic or otherwise) appear to be the most major drivers of overeating [3,4].
This may give some brief scope into a couple of the reasons why it seems that some can get away with what seem like disproportionately large intakes whereas others can't, but here's the thing - it's totally irrelevant anyway.
Your goals and progress will hinge on your behaviours and physiology. Comparing that to what somebody else is doing, and making assumptions as to what they're capable of getting away with (based on limited information) will result in nothing but self-defeat and frustration.
Resist the temptation to compare yourself to other people - we all have our own behavioural and genetic nuances. And although others may seemingly have a preordained advantage in the areas listed above, simply being aware of these factors allows you to make some proactive daily lifestyle changes to close the gap:
Find ways to increase your total NEAT volume
Spend less time sitting, whether in front of the TV, computer, or anywhere else. Set alarms or reminders at regular time periods to remind you to get up and walk around. Do more housework, spend more time outside. Park further from your destination. Get off the bus one stop earlier. Though seemingly minor suggestions, the cumulative effect can become significant.
Optimise your total intake of satiating foods like lean proteins and nutrient-dense, low-calorie fibrous plant foods.
The increase in satiety will ideally assist you to keep overall calorie intake lower over time. To take it a step further, track your calories and macros. If you know you have an event that will see you consume a lot of calorie-dense foods, set yourself a calorie buffer throughout the week. Caloric auto-regulation may not come as naturally as it does to others, but that doesn’t mean it can’t be acquired through practice and habit.
Take time to learn and understand how you respond to the above, either with yourself or a good coach/mentor, and set a plan accordingly. Who knows – plan your intake and expenditure wisely enough and you might find just yourself on the other side of the table!
1. Levine, J. (2004). Nonexercise activity thermogenesis (NEAT): environment and biology. AJP: Endocrinology And Metabolism, 286(5), E675-E685.
2. Long-term persistence of adaptive thermogenesis in subjects who have maintained a reduced body weight. (2008). American Journal Of Clinical Nutrition, 88(4), 906-912.
3. Weigle DS. (1994) Appetite and the regulation of body composition. [Review]. FASEB Journal 8:302–310.
4. O’Rahilly, S., Farooqi, I., Yeo, G., & Challis, B. (2003). Minireview: Human Obesity—Lessons from Monogenic Disorders. Endocrinology, 144(9), 3757-3764.