Satiety: How to Stop Feeling Hungry

Amongst the most commonly heard complaints amongst frequent dieters is that they either feel restricted in their food choices or they feel hungry all the time. If you’re overweight or simply trying to lose a few extra pounds, restricting some of your food choices and feeling a little hungry on occasion are things that you will have to deal with but by no means should they cause you to suffer nor make sticking to your diet overly difficult.

We’ve already discussed the importance of allowing yourself to enjoy some of the foods that you love in moderation in order to avoid feelings of restriction. Another important step is avoiding feelings of hunger that can sabotage your weight loss efforts by leading to overeating, excessive calorie consumption and weight regain… which I’m pretty sure we’d all like to avoid.

A complex control system

The biological processes involved in satiety that are supposed to help us control our food intake (just like most biological control systems) are complex. I remember first learning about them at a basic level in my undergrad degree and getting a headache. After university when I started learning more about satiety (but still only on a superficial level) as it affected weight loss I found the subject even more intimidating.  During my masters in nutrition my jaw dropped when I really started to learn the intricacies of satiety and how problems with its control mechanisms can lead to obesity. Then, when I finally got around to researching this article I thought, "what have I gotten myself into?".

To be honest that's how I feel about most of the articles I write. If you want real information you have to be willing to go the extra mile and look for it (or do what my clients do and pay me to look for it for you!).

With that said, I’ll try and summarize some of the current research on satiety while not skipping too many of the juicy details (the point of articles like this is for you to learn as much relevant information as possible).

Keeping your belly happy

Satiety is the process that stops further eating (by a reduction in hunger/ increase in fullness) after a meal is eaten. It’s what stops you feeling hungry until your next meal and may even cause you to eat less at that next meal.

It’s pretty conclusive from the research available that your food choices can and do influence satiety and the total amount of food that you consume in a day, which ultimately can affect weight loss {1,2}. So, knowing how to manipulate your own diet to keep you feeling fuller, longer is definitely a skill you want to master.

As I mentioned earlier, satiety is a complex process starting with the actual taste and pleasure of consuming food, moving to the actual physical changes in the shape of your stomach as it expands, then to the macro and micronutrients detected in your intestines and blood during digestion and the system even extends as far as detecting your level of body-fat to try and keep it constant over time. All of these stages involve a whole lot of chemical/hormonal signaling between your digestive tract and your brain {1,3-4}.

The easiest way to explain it all is to actually show you what foods are best at increasing satiety and explaining exactly why. Let’s get to it so you can keep that belly full and happy.

Protein seems to be the Golden Boy of the satiety world showing greater satiety power than the other macronutrients {5}; carbs and fat (which may actually have antagonistic effects to satiety due to fat being so delicious… don’t worry fat, we still love you).

One particularly interesting and more importantly, long-term study showed that a high protein diet (~30% of daily calories) actually reduced the total amount of food eaten in a day, which resulted in weight-loss in the long term without feelings of hunger {6}. Leptin, a hormone secreted by adipocytes (fat cells) can actually induce hunger when its levels drop low (which is what happens when people lose weight and this is why people often feel hungry when losing weight). It seems that a high protein diet actually increases your body’s sensitivity to leptin meaning lower levels don’t cause as much hunger.

Higher protein also seems to increase levels of two hormones PYY and GLP-1 which increase satiety and reduce food consumption and lowers levels of Ghrelin, a hormone that actually initiates hunger {7,8}. This is probably why high-protein diets have become so popular; higher levels of protein keep you feeling fuller for longer meaning that over time you actually take in less calories. There are other reasons that a higher-protein diet can aid in weight-loss (better muscle retention, increased Thermic Effect of Food) but we won’t get into them here.

Low-fat dairy (including protein powders), fish, lean meats, eggs and legumes (in that order) are protein sources that have shown strong effects on keeping you fuller for longer {9}. Include protein with every meal.

From the evidence available, I felt dairy products deserved there own little section on this list as higher dairy consumption has been shown to reduce hunger and calorie consumption when dieting {10,11}.

While part of this effect may be due to the protein content of milk (both whey and casein show pro-satiety effects), it may also be due to milks high-calcium content. There is some evidence to suggest that when calcium levels are low it can cause the body to seek out that nutrient in certain food {12}. As dairy foods are rich in calcium and often contain a lot of fat and carbohydrate, this “calcium appetite” can lead to over-eating of energy dense foods.

Humans need calcium in levels higher than virtually all other minerals (1000mg/day in adults) and this needs to come from the diet {13}. Low-fat dairy is not only an excellent source of calcium but the calcium in dairy is highly bioavailable (meaning it is absorbed well when digested) compared to plant sources of calcium like green vegetables {14,15}. That means that increasing your calcium levels (long term) may help to reduce appetite.

Reduced-fat milk, yogurts, cottage cheese, quark, cheese and even milk based protein powders are excellent sources of protein and calcium.

Fiber, which comes in many different types, is a form of carbohydrate that can’t be digested by the enzymes we produce in our digestive system. High fiber foods, as you probably already know from experience, have a powerful effect on improving satiety {16} (and promoting weight-loss).

There are a few different ways that fiber can decrease appetite;

• Fiber slows the absorption of digested food in the small intestine meaning there is a more steady release of nutrients into the blood stream, which can influence some of the appetite-control hormones mentioned earlier {17}
• Fiber reduces the energy density of food (which I’ll discuss later)
• Fiber can increase the volume of food in the stomach which also helps to control appetite

Wholegrain cereal products, legumes, fruit, vegetables, nuts and seeds are all excellent sources of fiber in the diet.

It’s worth pointing out that not all fibers are created equal. Highly viscous fibers (fibers that absorb water and thicken) seem to work better to improve satiety {17}. These can be found in foods like oats, rye, barley (especially in the form of porridges), konyaku and shiratki noodles (Japanese gelatinous food products that can be found in health food stores), psyllium seeds and fiber gums (guar, xanthan etc.). The latter items on this list are commonly used in diet foods because of their appetite suppressing effects.

Fruits and vegetables too, due to their high fiber and low energy density have shown benefits in reducing appetite {9,18} but need to be consumed in large enough amounts to have an effect. The take home message from that would be to eat plenty of vegetables and fruit (my policy on non-starchy vegetables is to consume them liberally and in large amounts).

There’s also evidence to suggest that some non-nutrients (substances found in food that are neither macro nor micronutrients) can also have beneficial effects on reducing appetite.

Caffeine (found in coffee and tea amongst other sources) has been shown to reduce food intake when taken before a meal {19}. So if you were looking for more reasons to drink extra “black gold” here’s another one to add to its ever-lengthening list of health benefits. On top of that green tea and capsaicin (the spicy component of chili peppers & powder) {20,21} have also been shown to help reduce hunger and further food intake.

Drinking some more coffee and green tea and adding chili powder to your food (start with a little and build up your tolerance if you’re not used to spicy food) might be useful ways of avoiding feelings of hunger when dieting.

Energy density is basically the amount of energy per unit weight (calories per gram) of food. One of the biggest variables in food that affects energy density is its water content. Think of it like this:

• 100g Spinach (High Water Content) = ~23 kcal
• 100g Cookies (Low Water Content) = ~460 kcal (20X more energy dense)*

 *Values taken from USDA Food Database

As fiber mostly passes through the body without providing energy, higher fiber contents can also lower the energy density of foods. So, it’s possible to reduce the energy density of a meal by adding more foods that are high in water content and fiber. This has been shown to reduce hunger and further food consumption at later meals {22}.

A very simple way of doing this is by adding vegetables (high in water and fiber, low in energy) to a meal or by having a salad or soup dish before the main meal {23,24}. The added volume of food with reduced energy density actual can keep you feeling fuller.

Reducing the energy density of your meals is very simple when you consider it just means replacing part of the meal with or simply adding extra vegetables or fruit. Making low-energy-density foods a bigger part of your diet can not only help you avoid hunger but considering most low energy foods are also very high in vitamins and minerals (fruits and vegetables) it also means you would be eating a much healthier diet overall.

This last section is more of an important point to be aware of than a food recommendation itself. Above I’ve listed how foods high in protein, fiber, calcium, water etc. can help improve satiety. However it’s very important to point out that when these foods were compared in solid forms versus liquid forms (same calories/macronutrients etc.) the solid forms generally proved to be much better at reducing appetite {2,25}.

One theory is that the body just might not be very good at realizing it’s consuming calories when taken in liquid forms {26}. This would explain why sweetened soft drinks are easily over consumed and can lead to obesity {27}. The best way to sum up how to apply this to your diet is:

“Don’t Drink your Calories”

I might make obvious exceptions for protein shakes and whole fruit smoothies but in general, get your food in solid form.

A notable exclusion

Some of you reading this list might be wondering why I haven’t mentioned the Glycemic Index (GI) of the foods. GI is a measure of how much a food increases blood glucose levels after eating it.

The reason is simple, the majority of long term studies and meta-analyses show no definitive effect on satiety from the GI of a food {28,29}. Also, GI is calculated for individual foods and the actual GI of a mixed meal is usually unrelated to the GI of the ingredients in that meal {30}. I was hugely interested in the possibilities of GI about 15 years ago but since then the majority of evidence would indicate that there are far more important things to consider when it comes to diet and health.

I’m not saying there is anything wrong with choosing low GI foods (the majority are generally less processed and high in fiber which are advantageous to health) but basing your food choices on GI is unnecessary at best and overly restrictive at worst.

A Hard Reality

After reading all this, what’s especially interesting is the fast that it's now very easy to understand why the majority of processed foods have very little affect at all on satiety.

Biscuits, cakes, buns, muffins and many desserts are generally made mostly with refined flour, sugar and fat meaning they’re incredibly low in protein and fiber and are very energy dense. On top of that they’re delicious and this encourages further consumption meaning they’re very easy to overeat. It’s no wonder that high consumption of such foods is associated with obesity (amongst other diseases) {33}. The foods themselves aren’t intrinsically bad as long they’re consumed in moderation. They’re nutritional make-up, however, makes moderation very difficult. They just don’t make you feel full.

I preach non-restriction and moderation with my clients; if you want to eat something, eat it, provided it fits your macronutrient needs. One way to better integrate less-satiating foods into your diet is to eat them together with foods that increase satiety. If you want a slice of pizza, eat it with a salad for added fiber and reduced energy density. If you want some ice cream, eat it after a bowl of oat porridge with protein powder (proats) for their appetite-suppressing effects.

Mix it up!

While most of the evidence I’ve presented here has shown reductions in appetite when eating certain foods in isolation, it stands to reason that combinations of these different foods (as is normal in a meal) would have even greater effects. With that in mind, meals consisting of a lean protein source, plenty of vegetables and some whole grains or legumes (along with a cup of coffee) might be the smartest way to stave off hunger while losing weight.

Even though appetite control might seem like only a small piece of the weight-loss puzzle (which it is) the science shows that reducing feelings of hunger on a diet is key to long-term success {30-32}. Like I said at the start of this article, even when dieting, there is no need to feel overly restricted or hungry. An enjoyable diet is one you can stick to long-term. Now start filling that belly.

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