Latin? Eughhh, boring! Don’t fall asleep just yet…“Ad-Libitum” translates to “at one’s pleasure”. Eating until I feel truly satisfied? That sounds like a diet I can get on board with and so I thought I’d explore the topic in more detail.
Some of you might already be thinking, what's the alternative? For this community, I am sure you will be familiar with idea of tracking your macros. That is, the logging and calculation you do to understand what the caloric breakdown of protein, fat and carbohydrates your diet consists of. There is no doubt that this is an effective way to build clarity on what you're consuming. But how practical is it? As you will see, that really depends on you and what you're trying to achieve. Whilst evidence finds macro tracking leads to a faster rate of weight loss than ad-libitum dieting, it also finds that adherence suffers (in other words, it's less sustainable). It then follows that researchers find intuitive eating is associated with less stress.
When we think about ad-libitum dieting with weight loss in mind, our energy balance (the balance of energy in and out) can be seen as a function of your appetite and your diet's satiety index. Breaking this down…
Our energy balance is where we find ourselves on the seesaw of deficit, maintenance or surplus over time. Let's nip this one in the bud quickly. If you consume more energy than you use, you're in surplus (and you'll put on weight over time) and if you consume less energy than you use, you're in deficit (and you'll lose weight over time). Nobody escapes the second law of thermodynamics. Think of appetite as your level of hunger - that really useful evolutionary mechanism that forces us to polish off a family sized bag of Sweet Chilli and Sour Cream Kettle Crisps in one sitting. When we give in to this urge, we start to become 'satiated' - that is, we start to feel full (in theory….). Mmmmm but go on, open another bag, you know you want to. Have it with that hummus dip you bought, go oooooooon. It's Friday after all!
This leads me on to your diet's satiety index. Different foods provide different levels of satiety per calorie. We know this from experience - controlling for calories, boiled potatoes fill you up a lot more than those pesky crisps.
You can therefore start to understand why being hungry, then consuming low satiety foods is a quick-fire way to find yourself in surplus. For those that have done macro tracking, we know what it feels like to plug in what you had for breakfast: oats, blueberries, milk, peanut butter, cinnamon, banana…. WAIT UP A MINUTE, YOU CANNOT BE SERIOUS 250KCALS FROM A GNAT'S WHISKER OF PEANUT BUTTER?
And yes, there actually is an index. In 1995, Holt et al compiled a paper called the 'Satiety Index of Common Foods'.
The chart below visualises the key findings. The reference food is white bread with a score of 100. It's by no means exhaustive but can act as a good reference point for key food groups. Dem croissants :/ (yarrrr Tilllyyyyyy, get me an oat chai turmeric flattie with a lowcal vegan triple choc almond croissant). Tae f*$k with not eating croissants - watching the world go by with a freshly baked pain au choc and a hot coffee from your favourite café? Oh God Yeh.
At the other extreme of the satiety index to potatoes would be something like table sugar which has practically no satiating effect. This is why eating more sugar tends to lead to overeating which is why it can be so fattening. One interesting perspective is that calorie for calorie, your favourite chocolate bar is no more fattening than let's say, broccoli. Intuitively though, which do you think you're going to end up consuming more calories from in a single sitting? Research has shown that increasing your diet's satiety index decreases energy intake, thereby supporting weight loss. Here’s another way to frame it - give yourself 10 appetite tokens per day. Cashing in those tokens on high satiety foods, ceteris paribus (yeh that's right I used more Latin), will reduce energy intake.
The next logical question is, ergo (couldn’t help myself), what determines a food's level of satiety? It's a long list, so whack the kettle on. Broadly we can think about (i) the volume of food and its contents (ii) a melting pot of psychological factors. Starting with the former….
Food Volume In short, more volume = more satiating. Well, isn't that obvious? Your stomach as nifty pressure receptors that quite literally signal levels of fullness to the brain. I am not sure I would have volunteered for this one, but researchers have shown that inflating an 'intra-gastric balloon' reduced hunger levels in participants. Apparently, it’s bona fide science (really getting in to this latin thing) … but would you feel hungry after this? I am not sure I would. Anyway, the point still stands. This is where it gets interesting (I hear your groans, this was never interesting Jacko. Simmer). Food volume on a calorie-equated basis is the inverse of caloric density. The result? The fewer calories per 100g, the more satiating the food is. An example that shook my pre-conceptions was nuts. I love scranning those cheeky bundles of joy. But at 579kcal per 100g (almonds), they're very energy dense. Although the two correlate relatively strongly, healthier food choices aren’t always more satiating. This article nicely visualises the energy density of different foods. This is why liquids can help us to feel fuller. Foods with higher liquid contents tend to be more satiating - think fruit and veg. Highly processed food can be easier to over-consume on the basis that it’s typically had it’s water content significantly reduced. Are you sensing a conspiracy theory? We are but mere puppets in a capitalist machine. On a more serious note, this isn't a free pass to start replacing meals with water. Remember, 'at one's pleasure'.
Fiber Quick 101 - fiber is a type of carb that struggles to be broken down by human digestive enzymes (high in oats, legumes, fruit, veg etc… it's really good stuff). What's the relationship to satiety then? Well, linking back to item one, fiber content roughly correlates to energy density (not in all cases, think back to those nuts). On this basis, higher fiber content therefore = lower energy density = higher satiety. Fiber also prolongs and amplifies the fullness effect (especially soluble fibers) through swelling in your stomach and intestines. Foods high in fiber tend to require more chewing too. More mastercation = greater satiety signalling. Lastly, short chain fatty acids (SCFAs) are the byproduct of fiber fermenting in our large intestine. SCFAs are subsequently absorbed by the brain, acting as another signal of fullness. Fiber seems to be pretty potent (in more ways than one am I right guys). Research has found that on average, every 14 g of fiber reduces ad libitum energy intake by 10%.
Protein My pre-conception was that more protein content = more satiating. The theory is that protein more potently activates satiety hormones (e.g. you may have heard of Ghrelin). But reading more research [1][2][3], it seems that higher protein doesn't necessarily translate to higher satiety. A more credible explanation is the 'protein leverage theory'. In short, the body monitors protein consumption to ensure we have enough of it. In other words, protein is more satiating than carbs or fats up to but not past the point where needs are met. Evolutionarily this does make sense - the body can't store amino acids (protein) in the same way it can with fats and carbs. Where this theory crosses over into macro tracking is the concept of prioritising your protein intake target before addressing fats and carbs. Although most of the research is limited (in that it comes from animal studies) there is some evidence that [1] humans have a higher preference for high protein diets following a low protein diet than after a high protein diet and [2] we have a lower drive to eat incomplete amino acid (protein) sources than complete equivalents (e.g. lower drive to eat broccoli than chicken). A general heuristic (sorry, that one’s Greek I think) is that the closer a protein matches human muscle in form and function, the more complete its amino acid profile. Anyway, bringing this one back into land, the practical question we should therefore ask is how much protein is enough? There will be a future post on this, but research has roughly settled on around 1.6g/kg/day. With regards to satiety, if you're below this figure then upping your protein intake from highly satiating sources first could be that low hanging chicken you’re after (or lentils for the veggies and vegans).
Texture The general principle here is that harder foods tend to be more satiating than softer ones. The same goes for viscosity. Again, this leads us back to mastercation. The harder or thicker, the more oral activity required (don't go there), improving satiety through both increased duration and signaling. The practical tip? If you have an option between turgid and flaccid, go turgid. This seems to contradict with what I said about liquids being a useful satiety tool - the key distinction here is your starting point. This is about moving from heavily processed apple juice to an organic granny smith, rather than deciding whether or not to have a glass of water with dinner
Glycemic Index (GI) Quick 101 - the rate at which a given food increases your blood sugar levels. The satiety index we’ve seen above would suggest this doesn't really matter. There is some evidence though that lower GI = higher satiety, but this is much more likely due to their relationship with items 1-4. In isolation, GI seems to have negligible effects.
Using the above detail, a few practical suggestions include:
Highly viscous foods like traditional Greek yoghurt or cottage cheese.
Legumes – kidney beans, lentils, chickpeas etc.
Fibrous Vegetables – broccoli, carrots, beetroot, cauliflower etc…
Fibrous Fruits – avocado, kiwi, peaches, blackberries, raspberries etc…
Lean meat and fish – turkey, chicken, halibut, tuna, shellfish etc…
Stop waffling on Jacko… how do we implement this to achieve weight loss? There are several strategies. The one summarised below does start from a point of tracking (I know… doesn't that defeat the point?), but it does facilitate greater independence further down the line.
First, build a clear picture of your current intake. This requires a food log and subsequent macro calculations. You could do this for a few weeks, tracking any changes in body composition you notice as you go.
Then stop tracking all of your macros but maintain a rough estimate of protein and overall calorie intake. If your body composition continues to change as intended, stop measuring overall calorie and protein, and start trusting your own understanding of which food choices will sustain your current intake.
If body composition slows down or stops, start adding in food items higher up the diet satiety index until you start to make progress again. Only reduce the intake of less satiating foods if you hit a wall with the above steps. Psychologically, there will be less friction adding in higher-satiety foods than removing lower-satiety ones.
Really though, the above still requires high level awareness and understanding of the energy density of different foods. For me this continues to be a slow learning curve. Let's say my maintenance intake is around 3000kcal. if I overeat by 600kcal one day (easily done, so that's 3600kcal) it’s going to be challenging to reduce my intake so that I am in a 100kcal deficit for the next 6 days to just reach maintenance over the course of a week.
Like with any attempt to lose weight, we find ourselves having to consider the importance of a behaviour change. We know that even on a good day conquering hunger can be a real challenge. I know for one that the little voice in my head will find all sorts of justification for opening that next bag of forest feast salted dark chocolate almonds (these things are addictive – sponsorship welcome). Research keeps demonstrating how powerful psychological factors are in determining real life outcomes. It's even been shown that humans perceive foods as less tasty on being told they are healthier [2]. We start to react to cues independent of consumption. A neat study conducted in 2005 powerfully demonstrated this - participants consistently consumed more soup from secretly refilling bowls than non-refilling ones. 74% of participants didn't even notice what was going on. Here, we see visual cues overpowering digestive ones (a tummy fulla soup).
So, what other tricks can we play on our minds to increase our perception of satiety?
Portion size
Researchers have found that labelling a food as more filling than another (even when it's not) reduces how much of that food they eat. Serving size can therefore act as an important cue. Multiple studies conclude, unsurprisingly, that larger portion sizes lead to greater energy intakes. This is the 'clean plate effect'. People tend to eat what they are given and research finds post meal satisfaction is not a function of portion size, but a meal's satiety level. Apparently, evidence has also shown that appetite doesn't have much intra-meal memory either. That is, eating more at breakfast doesn't result in an equivalent reduction in energy consumption at lunch or dinner. That age old advice of reducing portion size really has been proven as an effective technique for supporting weight loss.
Another trick we can play is with dinnerware - let me introduce you to the Ebbinghaus-Titchener size-contrast illusion and the Delbeouf effect (oh god, here he goes again).
The two orange circles in image 1 are the same size, as are the black filled circles in image 2. In practice, you'll perceive a bigger portion on a smaller plate (yeh yeh, within reason you lot - you're obvs going to go back for more if you start serving roast dinners in olive bowls). There is similar effect from introducing a high contrast of colour between your plate and the food on it (lol). With similar logic, it follows that using smaller cutlery can also result in lower ad-libitum energy intake (also lol).
2. Visibility
From experience this is a big one for me. In one study, people with highly caloric food visible on kitchen tops were found on average to be 30lbs heavier than counterparts with clear tops. If there are biscuits on our kitchen table they’re getting deleted!
3. Variety
I personally think this goes against the point of ad-libitum dieting but research does find reducing the variety of foods you eat leads to lower energy intake through intuitive eating. Through rose tinted glasses, reducing in-meal variety doesn’t necessarily mean reducing variety across the week - you could have 7 different but simple dinners every night of the week. Still sounds boring. Variety is the spice of life and all that.
4. Attention
Research consistently shows that distraction = increased ad-libitum food intake. You could call this 'mindless eating' and it chimes strongly with me. I have the propensity to consume more when I'm sat on the sofa watching England play uninspiring football than when I'm not (Sorry Southgate but we're left wanting more, in more ways than one). The opposite is 'mindful eating', personally one of my weakest nutritional links. It's a big psychological shift that I am trying to shine a light on - if you're going to sit down for 15 mins to eat, why not try to really enjoy it? Sorry to get philosophical but as our mate Eckhart Tolle once said "The quality of your consciousness at this moment is what shapes the future. Nothing has happened in the past; it happened in the Now. Nothing will ever happen in the future; it will happen in the Now."
5. Satiation point
In an attempt to be cancelled in my first ever piece of public writing, I reference a gender based study that showed men typically prefer to eating until they're very full, whereas women prefer to eat until they're almost full. I'd say this plays out accurately from my experience. Really though, to be more nuanced and genderless, our relationship with 'satiation' is on a sliding scale. Where do you think you sit on that scale? I know that I regularly continue past the point of initially feeling full, to a state of pure waddle. For me, knowledge of this point is harder to apply. I suspect though that if I start to adopt other tactics, in particular mindful eating, that I'll likely feel less need to keep going past that first threshold of satiety.
6. Speed
Another biggie for me that no doubt stems from mindless eating. The research seems to be mixed here, but evidence has shown that indepdent of palatability (think of that is tastyness), chewing has a direct link with satiety. This is why chewing gum has also been found to increase satiety and lower energy intake. On a practical note though, chewing gum isn't a sustainable tactic for reducing energy intake. The takeaway should again be around slowing down and enjoying that meal you just made! It also makes sense that the slower we eat, the more liquid we might consume alongside it, which we know to play a significant role in improving feelings of satiety.
7. Memory
Interestingly, research shows that remembering your previous meal can support reduced intake at a subsequent meal. This 'meal recall effect' is likely linked to some psychological trick of then believing the previous meal was larger, especially if you not only remember, but visualise it. Again, I see a strong link in the application of this point to mindful eating.
8. Tastiness
The more you like the taste of a food, the more of it you eat. Duh? Evolutionarily this is actually helpful. Why? Well, our cave dwelling ancestors would have liked the food that they needed to survive. And therein lies our modern problem - what we want is definitely not what we need. Wait… are you saying that I don't need that family sized tiramisu I just bought from Tesco to survive? Surely not.
Every cloud… the body learns to enjoy the foods we eat consistently. Not to get on my high horse or anything, but generally (apart from the aforementioned slips in control) I have become accustomed to eating what most would call a very healthy diet and, to be honest, I really enjoy it. Not only has it slowly become part of my identity, but I have really started to dislike very sweet things. The most relatable example I can think of is that I switched to 80%+ dark chocolate several months back and am starting to really enjoy it. In fact, very rich milk chocolate now makes me feel a bit nauseous. Do you have examples of your own?
Speaking with absolutely no parental experience… something Jamie Oliver said years ago stuck with me. He said he started to reward his young children with peas (yes you heard that right). Apparently, it didn't take long before all the children were craving peas. They started to grow an appetite for healthier food choices. For the parents out there, does this sound like a fever dream or an interesting experiment to try at home?
9. Social Effects
“Wouldn't you need friends for this to be relevant, Jacko”' - thanks dad. Really though, this again makes a lot of sense. Your environment plays a key role in your psychology. I have often watched myself mindlessly follow the lead at social events. Someone in the group is brave enough to plant their flag in the ground and announce with confidence to the table "I'm doing it, I'm having three courses". You give them that cheeky side eye and smirk, 3 courses it is! Whispers of "If you will, I will" ricochet around the table, and before you know it you've ordered cauliflower cheese and quadruple cooked fries as sides. A pint of ice cold Asahi too? It would be weird if I didn't!
This next study cracks me up… who is serving you seems to matter too! It appears that you could be 4x more likely to order dessert from an overweight waiter than a slim one!. Is this another cancellable reference? Oh well.
I do see instances where having awareness of the 'social effect' could be useful. I used to live in London and 'post-work pints' are predicated on pack mentality. A lot of the time I really didn't want to drink and found myself wishing I was sober and alone (crying? maybe). In those moments, taking a step back and ordering a lime and soda or 0.0% Guinness feels like a filthy rebellion. You watch that promotion slip through your fingers as your manager exclaims "don't be boring mate". The truth is that taking back control can start to feel empowering. As mentioned above, it starts to become part of your identity. Before you know it, you're the trend setter. I have used this technique to become a cultural icon amongst my peers. I don't have a research paper to reference on this occasion, but it's true.
I am really starting to blur the lines between the psychology of ad-libitum dieting and general willpower here. As I said, positive behavior change is a very strong predictor of the success of any attempt to lose weight (or in fact, of any change at all). With regards to diet, we also know intuitively that we are less likely to make decisions that align with our desired change when we are stressed, tired, or hungry. That's why it's so easy to crack a tinny open when you get in from a long day at the office. The tip? Design your week so that you're not sleepwalking through Sainsbury's late on a Thursday evening praying for Friday to come and go.
The healthiest approach here though is to find the root cause of the issue. This is a topic for another piece, but managing your long-term stress is always going to beat relying on willpower in resisting the urge to drop those Salted Caramel Gü Cheescake Pots (not even on offer either) in the basket.
10. Habitual hunger
I currenty have a strong mealtime consistency. For me this is an ad-libitum win. I have unknowingly entrained my hunger rhythm. As such, I don't get too many hunger pangs outside of these feeding windows. These are the finer details though and I can almost hear you screaming "that isn't how life works, ya toss$r". A more reasonable takeaway point? Aim to eat meals within +- 90 mins of when you usually would.
11. Frequency
Meal frequency debate really has been a central theme of dietary quackery over the years. One minute it's 17 micro-meals a day, the next it's 1.8 big ones with a 25 hour daily fast. With regards to ad-libitum dieting the research is a bit muddy but seems to find slight energy intake decreases on very low frequency meal plans and slight energy intake increases on higher frequency meals. One way I have been thinking about this is the surface area of contact between you and food. Simply put, more meals tend to equal a greater chance of overeating and vice versa. We're back to the question of what are you trying to achieve? For most of us, consistently eating 3-4 meals a day will be a more important predictor of ad-libitum success than radical shifts in meal frequency and timing.
12. Exercise
I was surprised by this one. There seems to be very little compensatory hunger response to increased energy expenditure. Meaning what? Well, contrary to what I thought, research finds that most exercise doesn't stimulate increased appetite. In fact, strength training is appetite suppressing, especially immediately post workout. I have mixed feelings about this one.
It does make sense in that exercise requires a sympathetic state (ready to move) which isn't congruent with rest and digest (parasympathetic). The hunger hormone Ghrelin also drops during and after exercise. To summarise, exercise tends to increase energy expenditure more than your appetite. Ceteris Paribus (there it is again), exercise can support ad-libitum deficits. The catch here is that the relationship between activity level and appetite is more of a J-curve. Exercise decreases appetite up to a point. For those training significant volume (e.g. endurance athletes) or involved in jobs with long days of manual labour, appetite then starts to increase again. Your body knows when you’re quite literally going the extra mile.
I am sure I eat more food post workout though….? I think this could link back to habituation. I likely plate up more because I think I deserve it. And well, maybe I do!
13. Sleep
Can you remember the last time a wellbeing related post didn’t mention sleep? Neither can I. One headline hitting study found that four nights of sleeping 4-7 hours rather than 8 increased appetite by 20-22%. Sheeeshhh. We also know that poor sleep reduces our metabolism, thereby widening that gap between our needs and what are we likely to over-consume. Sleep is a fundamental, non-negotiable pillar of wellbeing which I will return to in a later post.
14. Artificial Sweeteners
And lastly, we're on to artificial sweeteners. This may need a future post, but I am slowly being introduced to more and more evidence that suggests they're not as evil as I was led to believe. To keep it short and sweet (see what I did there?), they are a very effective method of supporting weight loss in ad-libitum dieting (or any kind of dieting in fact) when they displace higher calorie sweet foods. The most obvious example is standard coke vs. diet or zero. Substituting to diet or zero is an easy way to drop 150kcal. It all depends on your starting point. You wouldn't start replacing water with diet coke but if you habitually crack open a Fanta at 2pm every day, why not try the zero version instead? Evidence finds that it is the sweet taste that satiates us, not the actual sugar content. Let me be clear, they're a win if you're using them to replace actual sugar, but neutral at best if not.
Are you still with me? No? ok, that's fine. That’ll teach me not to blather on ad nauseam (last bit of latin I promise). It's time to wrap up. I've written a shorter post here that summarises the top practical tips and tactics you can use to reduce ad-libitum energy intake. Let me leave you with a well-known saying that should, more often than not, guide good decision making through all things ad-libitum. "Shoot the crocodile closest to the boat". Oh and for the economists out there – what’s next highest marginal return decision you can make to achieve your goal? For me, it's mindful eating. What's yours?
Summary – 10 big hitters
1. Introduce more volume: your stomach’s pressure receptors send signals to the brain telling it how full you are. Introduce foods with a lower energy density to increase volume per calorie and therefore satiety.
2. Fiber: research finds the bare minimum should be greater than 25 grams for women and 38 grams for men per day.
3. Protein: protein leverage theory leads us to conclude that we should be trying to meet our optimal protein intake each day. Research finds this to be 1.6g/kg/day.
4. Low-calorie liquids: this doesn’t apply highly caloric liquid versions of whole foods e.g. orange juice. This is about using water, decaf black tea and coffee (preferably not granulated), herbal tea and diet carbonated drinks (especially if you’re habitually drinking non-diet versions) to feel fuller, especially before and during mealtimes. Same goes for low calorie condiments, including herbs and spices.
Given points 1-4, aim for these kind of foods:
Highly viscous foods like traditional Greek yoghurt or cottage cheese.
Legumes – kidney beans, lentils, chickpeas etc.
Fibrous vegetables – broccoli, carrots, beetroot, cauliflower etc.
Fibrous fruits – avocado, kiwi, peaches, blackberries, raspberries etc.
Lean meat and fish – turkey, chicken, halibut, tuna, shellfish etc.
5. Dinnerware: with smaller plates, use the -Titchener size-contrast illusion and the Delboeuf effect to trick your brain in to thinking your portion size is bigger. The same goes for cutlery.
6. Serving size: the clean plate effect tells us that we tend to eat what we are given. Try plating up what you think will satiate you.
7. Availability: clear the kitchen tops – we all know from experience that if the crisps are out, they’re getting eaten. My coach, Chris shared a gem recently that also links to point 9. Past a certain time tell yourself (and your family) that the kitchen is now CLOSED. Why not hang a sign outside entrance to the kitchen or put sticky notes on the cupboards?
8. Distraction: limit ‘mindless eating’ by not eating on the sofa in front of the tv or on your phone. Find the power of now. Enjoy every bite, you deserve it!
9. Schedule: try to eat at consistent times. Aim for +-90 mins of when you usually eat.
10. Zzzzz: get proper kip. Sleep deprivation is a potent enemy of ad-libitum dieting. In fact, it’s an enemy full stop.
If you got this far and enjoyed it then vote below on what you’d like me to explore next. Although this is more of a personal project, I would be more than happy to shape its direction based on what readers might find useful
Commentaires