What are your first thoughts when you hear the words “junk food”? Most people probably think of things like pizza, chocolate, biscuits and crisps. And what is it that all of these types of foods tend to have in common? Well, they’re usually high in either sugar, salt or fat, or all three, and have often been manufactured to be hyper-palatable (to taste really nice)! In addition, they’re often foods that are not nutrient-dense. They are very likely to be energy-dense (or calorie-dense), but not nutrient-dense. There’s a big difference. To achieve a healthy, balanced diet, we want to aim to consume more nutrient-dense foods, which, as the name states, are foods that contain more or high amounts of nutrients (e.g. vitamins, minerals, fibre). Calorie-dense foods, also known as energy-dense foods, pack a lot of energy into a small amount of food, but often don’t contain a great deal of nutrients.
The British Nutrition Foundation provide the following thresholds for defining whether a food is low-energy-dense or high-energy-dense.
In a time where junk foods/high-energy-dense foods are becoming a bigger part of our diets, you may be asking…
Can you eat junk food and still lose weight?
And the answer, as is the case with pretty much everything in the world of nutrition and weight loss. It depends.
Energy Balance – What is it and Why does it Matter?
Even if you’re fairly new to the world of weight loss, you’ve probably heard of the importance of energy balance, and the importance of being in a calorie deficit to lose weight. But if not, let me give you a quick overview of this fairly simple, but extremely important concept you NEED to be aware of if you’re trying to lose weight.
You may have heard phrases such as “it’s all about energy balance, calories in versus calories out!” If you have no idea what this means, let me explain.
Every living cell requires energy to function, meaning every living cell in our body requires energy to stay alive. In addition, our body has to carry out a bunch of physiological processes every day, 24/7, 365 days a year, otherwise we would not survive. These include the more obvious things like breathing, our heart beating and our brain working away up there, but also includes things like our body metabolising the food and drinks we consume.
As such, our body needs a certain amount of energy per day. The amount of calories we need per day is known as our maintenance calories, as they allow our bodies to maintain themselves. If we consume around the same number of calories as our body needs, our weight will, apart from minor daily fluctuations, stay pretty much the same.
If we don’t give our body the energy it needs each day i.e. we consume less than our maintenance calories, then we will be in what’s known as a calorie deficit. Being in a calorie deficit is the most essential part of weight loss. Without being in a calorie deficit, you will not lose weight.
When you’re in a calorie deficit, your body is not getting the energy it needs, so it will use stored energy, such as muscle glycogen (glucose stored in our muscles) and fat to fuel itself. Hence, why, if you are not in a calorie deficit, you won’t lose weight. If you’re already giving your body the energy it needs to survive each day, it won’t utilise stored energy.
That’d be like someone filling up your car with fuel and then you driving to a petrol station to put more in. You wouldn’t do it.
This is when we’re giving our body more energy than it needs each day. In this situation, we would end up gaining weight as our body would store some of that additional energy. If people are looking to gain weight, whether it be muscle or not, if we’re not in a calorie surplus, we can’t gain weight. Remember, we can’t make something out of nothing. Your body can’t create extra mass if it hasn’t been given the energy to do so.
Calorie Deficits / Weight Loss and Energy-Dense Foods. Compatible?
If the advancements in knowledge around weight loss have taught us anything in recent years, it’s that as long as you’re in a calorie deficit, you can eat whatever you want and you will lose weight. So yes, this means, technically, you could eat just foods with very little nutrition and still lose weight as long as you remained in a calorie deficit. And that’s they key thing to remember, as long as you remain in a calorie deficit.
So, in theory, yes, you can eat junk food and still lose weight. But there’s a few things to consider outside of just being in a calorie deficit.
Junk Food and Satiety don’t Tend to go Together.
Previous research studies have found that one of the biggest barriers/difficulties with weight loss success is hunger (Sayer, Peters, Pan, Wyatt, Hill, 2018). Of course it is, when we’re hungry, we eat. When we’re reducing our dietary intake, we’re going to feel hungrier, which then makes us want to eat more, thus making it more difficult to stick with our new dietary changes.
In addition, research from behavioural studies indicates that including more low-energy-dense foods in our diet can improve satiety (feelings of fullness) and help us control hunger (Rolls, 2017). Low-energy-dense foods are simply the opposite of energy-dense foods. They are foods that provide us with a greater volume of food, but for less energy (calories) overall. Therefore, if we consume more foods lower in energy but higher in volume, this can help us feel fuller for longer, and make weight loss somewhat more manageable as it can significantly reduce hunger.
As such, it’s important that we try to aim for a balance of consuming mostly nutrient-dense, low-energy-dense foods that serve to fill us up and keep us fuller for longer, as well as including some of those previously forbidden treats, to help you maintain your sanity, and improve the likelihood of you sticking with your new dietary changes (explained in more detailed below).
Think about this: out of the foods/meals below, which are you going to feel more full after, a 500-600-ish calorie, nutritious meal, or the same amount of calories from chocolate cookies (about 7-8 cookies)? And if you say cookies, the fullness is unlikely to last very long compared to the top meal.
Why Cutting Foods out Leads to you Eating More of it
More often than not, people try and completely cut out energy-dense foods because they feel they’re “bad” or “you can’t possibly lose weight while eating chocolate!”
Well, what happens when you completely deny yourself of something you really like and/or want?
Yeah, you just end up wanting it much, much more. It’s not just toddlers who behave like this when they see another kid playing with a toy they didn’t care about for the last hour and now it’s the ONLY thing in the world they want.
It’s like me telling you to not think about a penguin right now. Don’t do it!
A common cycle people describe goes like this:
Cut out particular food(s) to help lose weight
Manage fine for the first few days (or maybe even weeks if they’re very strong-willed)
Get stronger and stronger cravings for the food(s) they have cut out
Give in and have some of the food(s) they’ve been cutting out
Hugely over-consume these foods because you convince yourself it’s just a one-off
It wasn’t a one-off, and you struggle to get “back on the wagon”
Regain the weight you’ve lost and end up heavier than you were than when you started and start the cycle again.
Previous research has found flexible approaches to weight loss that are tailored to each individual are more likely to make it easier to stick to any dietary changes, thus increasing the likelihood of weight loss success. In addition, it is thought that the level at which someone is able to adhere to their new dietary changes may be strongly tied to how different their weight loss “diet” is compared to their usual diet. If someone is expected to make drastic changes to their usual diet, this may make it less likely to be a successful weight loss endeavour (Gibson & Sainsbury, 2017).
In summary, changing too much and removing too much from your diet is likely to make it more difficult to stick to.
Energy-Dense Foods and Nutrient-Dense Foods are not Mutually Exclusive
Not all energy-dense foods are devoid of nutrition. There exists some foods which are both energy-dense, but also nutrient-dense. These can include foods such as nuts, which are classed as a high-energy-dense food (5.67kcal/g) but are also nutrient-dense as they include a variety of nutrients, such as unsaturated fat, protein, fibre, vitamins and minerals (Ros, 2010).
However, it’s still important to remember that examples of foods such as nuts, while they are nutritious, are still high in energy and we can very easily consume a significant amount of calories consuming a relatively small amount of them.
Why Eating Slower May Help you Eat Less
Something I’ve come to find with many people I speak with who struggle with their weight, is that many people report being fast eaters. In someone who doesn’t have issues with their weight, this wouldn’t be an issue. However, in those trying to lose weight that report being a fast eater, aiming to address this in an attempt to reduce their food intake could provide worthwhile benefits.
One study found that consuming a meal over a longer period vs shorter period (24min vs 6min) resulted in significantly greater fullness two hours after the meal (Hawton, et al, 2019).
In addition, I’m sure you’ve heard the old saying of “it takes 20 minutes for your stomach to tell your brain it’s full!” There is certainly some truth in this age-old saying.
When we consume food, this will set off the release of numerous neurotransmitters (our body’s little chemical messengers) which help parts of our body communicate with other parts. One neurotransmitter that is released is known as cholecystokinin. I realise that’s a bit of a mouthful, hence why I’m glad it’s more commonly known as CCK. CCK is thought to play a significant role in our feelings of fullness, which may ultimately reduce how much we eat, if we eat slow enough.
CCK levels have been found to start rising after ~10 minutes after we begin a meal and keep rising until around the 30-minute mark (Moran & Kinzig, 2004). Therefore, you can see how, if you wolf down your meal in less than 10 minutes, you don’t give your body’s neurotransmitters a chance to catch up with the fact that you’re eating, so you can eat a significant amount of food in a short space of time before feeling full.
So, to stay on topic with this article’s title.
If you eat foods that have a high-energy-density, it’s easy to consume a lot of calories quickly. Whereas if you consume foods that have a low-energy-density, you’re likely to take longer eating these foods, which could have a positive impact on the amount of food you need to feel full, and may even help you in leaving some food on your plate.
To answer the question of:
Can you eat junk food and still lose weight?
The answer is yes, however, it is important to find a balance of consuming mostly low-energy-dense, high-nutrient-dense foods. These foods will provide a much greater effect in helping with feelings of hunger, which has been identified as one of the main difficulties with weight loss. It’s pretty hard to ignore hunger, right?
For weight loss to occur, you must be in a calorie deficit, without which you would not lose weight. Therefore, it is very possible to have a flexible approach to weight loss, meaning the inclusion of “junk food” in your daily diet is absolutely fine as long as you remain in a calorie deficit. However, as discussed, such foods don’t have as much of a positive effect on hunger, therefore if a significant portion of your daily calories come from foods high in energy and low in nutrition (such as fiber, which help with feelings of fullness), then sticking with your dietary changes may prove more difficult.
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If you made it this far, well done!
I hope you found the information in this article interesting and helpful. If you have any questions or comments, drop them in the comment box below and I’ll get back to you as soon as possible.
Gibson, A. A., & Sainsbury, A. (2017). Strategies to Improve Adherence to Dietary Weight Loss Interventions in Research and Real-World Settings. Behavioral Sciences (Basel, Switzerland), 7(3). https://doi.org/10.3390/bs7030044
Hawton, K., Ferriday, D., Rogers, P., Toner, P., Brooks, J., Holly, J., Biernacka, K., Hamilton-Shield, J., & Hinton, E. (2018). Slow Down: Behavioural and Physiological Effects of Reducing Eating Rate. Nutrients, 11(1). https://doi.org/10.3390/nu11010050
Moran, T. H., & Kinzig, K. P. (2004). Gastrointestinal satiety signals II. Cholecystokinin. American Journal of Physiology-Gastrointestinal and Liver Physiology, 286(2), G183–G188. https://doi.org/10.1152/ajpgi.00434.2003
Rolls, B. J. (2017). Dietary energy density: Applying behavioural science to weight management. Nutrition Bulletin, 42(3), 246–253. https://doi.org/10.1111/nbu.12280
Ros, E. (2010). Health benefits of nut consumption. Nutrients, 2(7), 652–682. https://doi.org/10.3390/nu2070652
Sayer, R. D., Peters, J. C., Pan, Z., Wyatt, H. R., & Hill, J. O. (2018). Hunger, Food Cravings, and Diet Satisfaction are Related to Changes in Body Weight During a 6-Month Behavioral Weight Loss Intervention: The Beef WISE Study. Nutrients, 10(6). https://doi.org/10.3390/nu10060700