The marketing is always perfect.

Anti-aging, fat blasting, muscle building, mood enhancing - the list is always longer than the Great Wall of China.

So why are they so popular?

How Smoothies Could Be Making You Fat

As part of the Fit'n'Flexed personalised diet plans, I successfully work with people to ensure they consume the foods they love and still lose weight. 

No foods are off limits.

But trouble arises when people either make their own smoothies or visit places where the nutritional value of a smoothie is NOT consistent, which can wreak havoc on fat loss efforts.

People are critical of smoothies all the time: "They are so full of sugar!" but the sugar isn't the issue, it's the overall calories in the sugar, the fat, and everything else the drink contains, and sometimes, what it doesn't contain.  

Picture this - for lunch you eat a chicken breast, serving of white rice with lettuce and half an avocado. Depending on the serving sizes, that's around:

Protein: 27 grams

Fat: 18 grams

Carbohydrates: 40 grams

= 430 calories

Now that's a decent meal, and would go towards your overall macronutrients for the day quite nicely; particularly impressive is the protein content.

One who has consumed this meal would generally think: "I had a great lunch...I don't need to eat much else."

But now onto the person who has a smoothie. I've seen some smoothies being made with bananas, honey, walnuts, yoghurt, peanut butter, milk etc. The protein and fibre content is quite low, but the fat and carbohydrate numbers are quite high.

Also, sometimes the person buying the smoothie thinks it can't possibly add weight because it's a "healthy" drink. 

Now don't get me wrong - this smoothie is okay, depending on whether you are tracking the calories (more specifically the macronutrients) in it or not. The problem is most people are NOT. 

By the time you look at each item in the smoothie and add it up, the macros would read something like:

Protein: 12 grams

Fat: 31 grams

Carbohydrates: 50 grams

= 527 calories

So in the smoothie there's more carbs (not the problem for your carb phobes) nearly double the fat, and LESS protein, and not much fibre.

Again, and I must stress this, there's nothing wrong with having this in a diet, what I'm saying is people don't know what's in it.

Then, the next big problem.

"Oh, I only had a little smoothie an hour ago, so I can easily have the healthy chicken breast salad and rice for lunch, sure, let's sit down..."

And so the problem starts - the weight loss subject consumes a bomb load more calories on that day then what they realise, even if they feel somewhat full. 

The other issue? One of the most important ones?

We know that protein is the BEST macronutrient for satiety (keeping us full), whilst fibre also packs a good punch (1,2).

The shake lacks the fibre and protein content the food has. This means the weight loss subject could be more likely to want more calories after the smoothie.

Now this won't ALWAYS be the case. It's not quite as simple as examining the macronutrient intake and saying: "more protein, more fibre, that's better."

This is because of energy density, which is a key characteristic difference between solids and liquids of the same energy content, and seems to have a greater influence on appetite and the related hormones in comparison to the macronutrient content (3). 

But the point still remains, eating the food for a higher contribution to your protein intake and likely better satiety is the go...all for 100 less calories too - and this is the point.

Fat Loss: Liquids Vs Solids For Satiety - Keeping You Full

Previous data tells us solid foods lead to superior and more prolonged reductions on hunger in comparison to liquids (4-7).

Specifically, one of the studies found the liquid drinks suppresed the desire to eat below baseline for 3 hours, while a bar was successful for 5 hours. 

However, in another paper, when Coca-Cola or cookies were compared, there was no difference in satiety (8).

So it's not always going to black and white - it can depend on the comparison and the macronutrient content.

However, this article is NOT about bagging smoothies, it's about being critical about some of the contexts smoothies find themselves in - and how to fix it! Because at the end of the day - weight loss is about negative energy balance, and we can't achieve that by eating more calories then we burn!

Are Smoothies Good for Weight Loss? 

There's no issues with smoothies for fat loss - providing they are accounted for and you know what's in them.
 
But the best tip I can give you is that protein shakes, or in other words, your own DIY smoothies, are much better.
 
You can control the calories, and the fibre and protein. You can even consume this WITH food, something that I do, when hunger really is hanging around.
 
That way, I have complete control over the calories and macronutrients and can weigh it up against my daily intake as I push on with my fat loss efforts.
 
Again, you can enjoy the smoothie, just make sure you understand how it can derail your fat loss campaign, and how to prevent it. 
 

"Stay Fit, Stay Flexed!" 

 

References

(1) Yancy WS Jr, Olsen MK, Guyton JR, Bakst RP, Westman EC. A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia: a randomized, controlled trial. Ann Intern Med 2004;140:769–77.

(2) Clark MJ, Slavin JL. The effect of fiber on satiety and food intake: a systematic review. J Am Coll Nutr. 2013;32(3):200-11. doi: 10.1080/07315724.2013.791194.

(3) Bell EA, Castellanos VH, Pelkman CL, Thorwart ML, Rolls BJ. Energy density of foods affects energy intake in normal-weight women. Am J Clin Nutr. 1998;67:412–420.

(4) Mattes RD, Rothacker D. Beverage viscosity is inversely related to post-prandial hunger in humans. Physiol Behav. 2001;74:551–557.  

(5) Leathwood P, Pollet P. Effects of slow release carbohydrates in the form of bean flakes on the evolution of hunger and satiety in man. Appetite. 1988;10:1–11.

(6) Sepple CP, Read NW. Gastrointestinal correlates of the development of hunger in man. Appetite. 1989;13:183–191.  

(7) Rothacker DQ, Watemberg S. Short-term hunger intensity changes following ingestion of a meal replacement bar for weight control. Int J Food Sci Nutr. 2004;55:223–226. 
 
(8) Almiron-Roig E, Flores SY, Drewnowski A. No difference in satiety or in subsequent energy intakes between a beverage and a solid food. Physiol Behav. 2004;82:671–677.