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Weight loss and late-night meals ...
In nutrition (and fitness) it's hard to differentiate between fact, myth and personal bias.
The consensus estimate can be wrong
There is a fancy term in the equity market called a "consensus estimate". This estimate is a forecast of a public company's projected earnings based on the combined estimates of all equity analysts that cover the stock.
The consensus estimate is a smart way for the analysts to transfer risk, i.e. "nobody was ever fired for recommending the consensus". It is essentially a self-fulfilling prophecy. If a particular analyst's trades don't reflect their consensus, then the other analysts will adjust to come closer to the new signals.
Dieticians are the same. Who can blame them?
If they are asked "Should I avoid eating late at night if I want to lose weight" they will provide a consensus answer. This is to say that they can answer, but not correctly.
What do you think the consensus answer is?
Here's a hint. "Night-time can be a danger zone if you're trying to lose weight", says Dietitians Association of Australia spokeswoman Kate Gudorf.
What does "common sense" tell us about late-eating?
How do you think about that answer? No that's not bad grammar - in what context do you think about that answer? It's undoubtedly the box that student dietitians in Australia had to tick to get a passing grade.
Do you think that student dietitians in Spain and South America, for example, would answer the question the same way? Undoubtedly not.
If the "eating late" proposition were valid at a population level, then no one in Spain or South America would ever be able to lose weight. And those in the USA would be successful in losing weight (I don't see many Americans going out for their main meal after 9 pm).
Guess what? The average weight of the population of Latin America and the Caribbean is 67.9 kg compared to 80.7 kilograms for North America. Eighty-percent of the US population is overweight (the same in Australia).
"The cook mentioned she ate her evening meal after 9 pm: a time that was typically marked for dinner in her country, but branded as unusually late to eat in Australia for fear it could lead to weight gain.
She said she had heard of this weight gain myth before and reminded me that in Spain and many countries across South America, millions of people had eaten dinner between 9–11 pm for years."
So "common sense", tells us that the mere fact of eating late is not a cause of obesity.
What does the research say about eating late and weight gain?
A small new study suggests meal timing doesn't make a difference for weight loss, as long as you're eating the same total amount of calories.
Researchers looked at 41 overweight adults over 12 weeks. Half the participants ate most of their calories before 1 pm, while the remainder ate a majority of calories after 5 pm. All the participants ate the same healthy, pre-prepared meals throughout the study.
By the end of the study, participants from both groups had lost weight and had lower blood pressure, regardless of when they ate.
"We did not see any difference in weight loss for those who ate most of their calories earlier verses later in the day", said study author Dr Nisa Maruthur. Dr Maruther is an associate professor of medicine, epidemiology and nursing at Johns Hopkins University in Baltimore.
Dr Maruther presented this research last week at the American Heart Association's 2020 Scientific Sessions. So this will be the new mantra for doctors in America, for their patients.
Could it be that 41 overweight adults have redefined the consensus answer to eating late and losing weight?
Not so fast, some researchers suggest that eating late at night could be more dangerous than we think.
Eating late may be dangerous for our health
Research from the University of Pennsylvania found that eating out of hours raises the level of glucose and insulin in the body, both of which are causes of type 2 diabetes.
This study compared eating:
"Eating later can promote a negative profile of weight, energy, and hormone markers", said Namni Goel, a research associate professor of psychology in Psychiatry in the division of Sleep and Chronobiology.
Now hang on to your hat. This finding is based on studying "nine healthy adults". Yes, NINE.
Perhaps you could smell a conference coming on? And you'd be right! The recommendations - based nine people - were presented at the SLEEP 2017, the 31st Annual Meeting of the Associated Professional Sleep Societies LLC.
Are there any studies with more participants than your extended family?
We're in luck.
Dr Daisy Duan, Dr Maruther's colleague at Johns Hopkins University School of Medicine, presented at the same recent 2020 Scientific Sessions of the American Heart Association.
Dr Duan's study analysed 3862 participants from the large public access dataset of Look AHEAD. Specifically, she examined if weight loss outcomes in Look AHEAD were related to breakfast consumption frequency (BCF). BCF is simply a value between 0 and 7, where 0 means no breakfast and seven means eating breakfast every day.
Across 4 years of data, breakfast consumption was associated with greater weight loss (in subjects who also received intervention focused on behavioural, nutrition and activity themes). In fact, each 1 day increase in average BCF was associated with an additional 0.43% weight loss (over the four years).
This is a credible analysis.
Dr Duan's study begs the question of her colleague Dr Maruther's findings. In the latter's study, the people who ate more after 7 pm were allowed to consume 50% of their food before 7 pm. If they ate breakfast, then that may have "compensated" for them eating late the night before - according to Dr Duan's results.
Dr Maruther's study did not record meal timings other than "before 7 pm" and "after 7 pm". Perhaps people who eat late and then do not eat breakfast WILL gain weight. These studies don't tell us the answer.
Are their other clues?
A 2019 meta-study of eating times and weight loss concluded that time-restricted feeding "achieved a superior effect in promoting weight-loss compared with unrestricted time in meal consumption".
The conclusion was based upon 485 eligible subjects.
The problem isn't eating late, it's what we eat
So what to do?
Eating late in itself is not the problem. There is no credible evidence in the research above to suggest that it is or is not associated with weight loss or weight gain. And looking at it through a cultural lens it doesn't make sense that eating late is the core problem.
The consensus estimate - that late eating leads to weight gain - doesn't hold up. It's not the correct answer.
We don't know the correct answer because they did not ask the question.
But most likely it is to do with what we eat rather than when we eat.
Five tips to get late-night snacking under control
Late-night snacking is often more likely convenient high-fat or high-sugar foods such as ice-cream or chips, which can contribute to weight gain in the long-term.
Whatever the time you eat is, eat well, to your appetite, and stop before you're full. Late night, that's easier said than done. You can avoid late-night food cravings and midnight fridge raids with a little awareness and planning.
Here are five tactics to use when you're fighting the temptation to eat something late at night:
If you are going to eat late, watch what you eat. Eating extra calories and junk food will inevitably lead to weight gain. On the other hand, eating nutritious food in balance with your total daily calorie needs is unlikely to lead to weight gain, despite what your dietician says.
That doesn't mean that eating late is healthy.
There are numerous studies which report that eating late is associated with metabolic diseases. We'd need to check metabolic health between late-night dinner cultures and others before really knowing the cause.
In the meantime, nothing beats eating real food, not too much of it, and exercising regularly.
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