The Last Supper Effect
Exploring one of intermittent fasting’s most nefarious side effect
My partner often calls me a weirdo for this, but one of my favourite pastimes is experimenting with my body’s physical limits. As a medical student at my junior college year, I underwent quasi-military training with the first responders unit for six months, pushing my physical boundaries with very little to no food. It was intense, but I was surprised at what the body was capable of doing in extreme conditions.
This experience led me to start my adventures with diets, shifting in between diets, quick to follow the ever-changing internet trends. My latest musing was intermittent fasting. Having tried different forms of the diet, including the 5:2, 6:1, and 16:8 routines, I became a keen observer of its benefits and quickly became an evangelist to friends and family members.
Late last year, I successfully acclimatized to a consistent 22 hour daily fast, allowing my body a daily 2-hour eating window. While this was undoubtedly encouraged by my WFH, which minimized energy expenditure, I found some genuine comfort with this diet. The one meal-a-day routine meant I spent significantly less time on eating, bolstering my productivity. Additionally, I saw a positive side effect in respectable weight loss and a leaner physique.
Not long after, like I always do, I discovered a new ‘diet’ to try. I stumbled upon the concept of intuitive eating, introduced by nutritionists Elyse Resch and Evelyn Tribole in their 2012 book. The concept itself is simple to understand and underscores the idea of eating in alignment with natural hunger and satiety cues instead of emotionally or externally triggered eating. It was more of a diet killer than a conventionally defined ‘diet.’
I expanded on the concept in more breadth in a separate post. Still, it was also in that book that I discovered an interesting side effect to the intermittent fast that I never quite realized until it was brought to my conscious attention by Elyse and Evelyn. Enter: the last supper effect.
In essence, the last supper effect describes excessive consumption of foods we enjoy or fear going without as a way to pre-empt the restriction to come on a diet or as a post-diet reward. It is the now or never mindset with eating when you give yourself full permission to indulge, even if you don’t really want to. It’s an unnatural urge because, in your mind, you believe that it’s the last time you’ll get to have that food or drink.
Usually, at the end of my fasts, I become so famished that I glorify my singular opportunity for sustenance and treat it as the last supper. As a result, I often leave the dining table physically uncomfortable, having exceeded my satiety threshold. What entails is often a lethargic and dull afternoon.
A 2008 study by Stanford University Professor Eric Stice and colleagues followed 496 adolescent girls from a diverse set of cultural and geographical backgrounds for five years. At various follow-up assessments, a significantly higher body mass index was found in those who reported fasting compared to those who didn’t.
Eight percent of the participants demonstrated bouts of recurrent binge eating episodes over the 5-year follow-up. An additional five percent showed onset of bulimia nervosa. Collectively, this study's results support the dietary restraint theory, a well-known phenomenon in the nutrition sphere proposing that dietary restraint induces counterregulatory responses, reduces sensitivity to satiety signals, and can result in disinhibited, binge-like eating patterns.
Other experiments have found that acute periods of marked caloric restriction, as in the case with fasting — often precedes the last supper effect — increase the reinforcing value of food. Stice thinks this may explain why fasting increases the risk of binge-eating, leading to the last supper effect.
Not only did the last supper effect incentivize compulsive eating behaviors and lethargic post-prandial sessions, but it was also strongly associated with a paradoxical increase in weight, further proving the posit that diets are ineffective at accomplishing their main purpose.
This is exactly what intuitive eating tries to address and resolve. It underpins the idea of allowing yourself any type of food, anytime you want it. While it may seem dangerously risky, the theory is that it feels less essential to eat it to the point of discomfort. On the contrary, telling yourself, you can’t have something gives it undue power and allure. “It’s the permission paradox,” says Tribole. “When you have permission to eat, the food still tastes good, but you remove the urgency.”
