There is a smorgasbord of options to sink one’s teeth into:
Multiple choices do not make decisions easy. It’s quite the opposite in most instances. Assessing the competing claims of these various options can be a recipe for indigestion. A business framework approach to dieting suggests that the decision is along three axes:
- What to eat (fruits, vegetables, carbs, proteins).
The quantity question has been researched since the 1930s, and studies have shown the benefits of reducing calories. Data is available in microbes, multiple animals, and in humans. Reduced intake provides many benefits that we seek – weight loss, a desirable biochemistry profile, and healthy aging. (Please note that aging benefits in humans are deduced based on improved biochemistry markers and not proven directly.) Our hunger for optimisation, however, makes us forage beyond this simple and proven intervention.
The debate turns spicy at ‘what to eat’. Proteins, carbs, fats? From animals, plants, dairy? Each diet has its own supporters who are ready to devour the arguments of the other camps. The conflict exists because the data is confusing. Also, history suggests that today’s flavour-of-the-day diet can leave a bitter taste in the mouth tomorrow.
Remember the now discredited US low-fat craze in the 1990s? It is an unpalatable story and can make one cynical about any nutrition ‘truths’. Another example is eating multiple meals in a day. After a total reversal, today’s special is to confine all eating within a short window.
The data does not provide certainty, because most studies are conducted in animals (some in microbes). The applicability of such results to humans is an open question. The timeframe of studies is short (multiple weeks). As a contrast, a cardiovascular drug is studied in humans for about five years.
Furthermore, studies yield contradictory results on safety and efficacy of these interventions. For example, an April 2022 review (bit.ly/3YXgf3p) in the journal Cell mentions some long-term risks of the ketogenic (especially with animal protein) and vegan diet. A US National Institutes of Health (NIH) study (bit.ly/2HBN1lr) showed that the keto diet does no better than a ‘regular’ diet of equivalent calories in terms of daily energy expenditure. A common platform in most of these plans – and a facet often overshadowed by the extreme aspects of the diets – is to reduce processed food. An NIH study (bit.ly/2M1wVWc) found that daily intake on a diet of primarily processed food is about 500 kcal higher than on a diet of unprocessed food.
The final axis is the time window for eating. A 2012 study (bit.ly/3G8Ty42) in mice nourished this trend of eating all meals in an 8-hour timeframe. A 10-12-hour eating window is a traditional eating pattern, and is in sync with an 8-hour sleep cycle and some fasting before and after. It is ironic that we needed a mice study to feed us our own traditions.
As with the other nutrition questions, long-term data supporting extended daily fasting in humans is limited, and there are debates within experts on a severely restrictive eating window (less than 10-12 hours). An April 2022 study in The New England Journal of Medicine (bit.ly/3WHUAuj) showed no benefits after a year of eating in an 8-hour time window when compared to consuming the same reduced calories without time restrictions.
In general, a review of the menu of diet options suggests that looking beyond the table offering reduced calories and reduced processed food, one is faced with plans that veer near extremes, such as eliminating entire food groups, entire sources of food, or large swathes of eating time. Extreme stands can make for catchy headlines and bite-sized book titles. But the risks and benefits to the broader population over and above eating less (and less processed food) are still being debated.
The common ground seems to be with the commonsense principle of moderation. These same principles were outlined by Michael Pollan in his 2009 book, In Defense of Food: An Eater’s Manifesto. Pollan concludes:
- We can add ‘Within 12 hours’ to his list.
- And, as with physical exercise, consistency is better than intensity.
Perhaps these five points can make a savoury resolution for this New Year?
