Liquid vs. solid calories while on GLP-1s:

Bruce Campbell

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Nearly 20 years in the fitness world means I've heard the same advice over and over, whether the goal was a bulk or a cut: chew your calories, don't just pour your macros down your throat with shakes or smoothies.

Once I'd spent a month on Reta feeling completely full, and noticed that liquid calories made it simpler to reach my daily macro and calorie targets, I wanted to look at the actual research behind that advice.

As far as I can tell, the two big arguments for solid food mostly stop mattering when GLP-1's are in the picture:

1: Satiety and Digestion: Food you chew takes longer to break down, which triggers fullness hormones such as GLP-1 and peptide YY. Liquid calories, on the other hand, move through the stomach fast and frequently don't get registered by the brain, producing a "stacking effect" in which people take in additional calories without any sense of being full.

— Given that a GLP-1 agonist (Reta) is already binding to GLP-1 receptors, getting satisfied from a medium calorie protein shake appears to make hitting my numbers easier than feeling stuffed after half a meal that delivers fewer macros.

2: Blood Sugar and Nutrition: Whole foods bring fiber and intact cellular structures that delay nutrient absorption, which heads off the sharp insulin spikes and crashes tied to liquid diets.

— If Reta triggers insulin release when glucose runs high, suppresses inappropriate glucose output from the liver, and also slows gastric emptying, doesn't that make this point largely irrelevant too?

I get that there are essential micronutrients and vitamins you simply can't obtain from living on assorted shakes and fruit smoothies alone, and I'm certainly not arguing that an all liquid diet makes sense, given the short and long term GI problems it would cause.

What I actually want to know is this: assuming proper macro and micro nutrient supplements plus fiber support, would someone chasing fat loss and muscle gain be harmed or held back by a diet that's 60-70% liquid? If the chief worries are unintentional extra calories, reduced satiety, and blood sugar swings, wouldn't a triple agonist pep like Reta cancel those effects out?

Any insight or pushback on this line of thinking is very welcome.
 
In my opinion, once you're on GLP's, there's no reason to bother with fad diets. Simply eat as you normally would.

From what I've read, when people talk about liquid calories, they usually mean things like juices and sodas. A protein shake isn't really what's being referred to.
 
Not on Reta, but it might come down to dose. Until my third dose of 7.5 mg Tirz, my body (weight wise) was pretty untolerant to carbs. Just a thought.
 
Estarossa19 said:

In my opinion, once you're on GLP's, there's no reason to bother with fad diets. Simply eat as you normally would.

From what I've read, when people talk about liquid calories, they usually mean things like juices and sodas. A protein shake isn't really what's being referred to.

In my case, two of my daily ‘meals’ are protein/fiber shakes, which makes it simpler for me to reach my macros and calories, and then lunch is one solid meal — usually a big serving of vegetables plus some extra protein, most often fish.

Given the way the fitness world tends to look at calories from shakes versus solid food, my guess is the immediate response would be that this isn’t a good approach, because a person should be getting their calories from solid food. But the core reasoning behind that view doesn’t really seem to apply on Reta. I could be wrong.

I’m not talking about “liquid diets” such as juice cleanses or other fad diets.
 
plant_lady said:

Not on Reta, but it might come down to dose. Until my third dose of 7.5 mg Tirz, my body (weight wise) was pretty untolerant to carbs. Just a thought.
Up to this point, my body has handled carbs fairly well, though I’m only injecting 1mg every 5 days. It’s been 5 weeks and appetite suppression has remained steady. Currently I’m getting 120-150g of carbs per day, and the sole thing I’ve noticed is that my morning lifting stamina is a bit lower.
 
To me, the strongest point is probably the micronutrients found in whole foods that shakes and powders simply don't provide. Hundreds of compounds and trace minerals the body can use are present in meats and plants. Would combining the two work? Have small meals made of whole foods, then use a shake as a sweet treat to help hit your targets?
 
While I was in my weight loss phase, my daily targets were 1800 calories and 100g of protein. On certain days, the sole route to that protein number was a scoop of protein powder.

Other times, a protein bar served as my dessert.

These days, with maintenance as my focus, I'm largely sticking to real food and paying no attention to calories or macros
 
kakiebean said:

To me, the strongest point is probably the micronutrients found in whole foods that shakes and powders simply don't provide. Hundreds of compounds and trace minerals the body can use are present in meats and plants. Would combining the two work? Have small meals made of whole foods, then use a shake as a sweet treat to help hit your targets?

Yes! That point came up in the post I originally made.

And further down, I’m already doing both — though I might have to add more to hit my daily protein target 🙁

Bruce Campbell said:

In my case, two of my daily ‘meals’ are protein/fiber shakes, which makes it simpler for me to reach my macros and calories, and then lunch is one solid meal — usually a big serving of vegetables plus some extra protein, most often fish.

Given the way the fitness world tends to look at calories from shakes versus solid food, my guess is the immediate response would be that this isn’t a good approach, because a person should be getting their calories from solid food. But the core reasoning behind that view doesn’t really seem to apply on Reta. I could be wrong.

I’m not talking about “liquid diets” such as juice cleanses or other fad diets.
 
Interesting question/topic. I'm in the same situation — reaching my protein and calorie targets is far simpler when I rely on shakes plus a single main meal each day. On top of that, I take fiber supplements.

As I see it, a diet made up of 60 to 70% liquid isn't automatically bad or a step backward for fat loss and muscle gain while using reta, as long as protein is the priority and you're training consistently. Naturally, I view it as a diet for a particular phase instead of something permanent, and I'll certainly move back to mostly solid foods once I get near a maintenance dose or start tapering off.

That being said, my stomach doesn't always feel great about how much whey/dairy I'm consuming.
 
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That's a pretty big chunk of your diet coming from drinks. That said, if your macros line up and you're hitting enough micros and fiber, I'd say go for it. When solid food is tough to eat in the amounts you need, and the choice is between being malnourished and getting enough kcal, then just drink the shake or smoothie. Even if solid food were superior across the board, you shouldn't sacrifice good while chasing perfect.
 
Bruce Campbell said:


I’ve been in the fitness realm for almost 2 decades and one of the tips I’ve always heard while attacking both bulking or cutting cycles is to EAT your calories and not to hit your macros simply from drinking them via shakes or smoothies.

After a month of being fully satiated on Reta and finding it easier to hit my macro / caloric goals for the day with liquid calories, I decided to dig into the science behind why people say that.

From what I see, the main two points to eating your calories are basically made moot by GLP-1’s:

1: Satiety and Digestion: Solid foods require chewing and take longer to digest, which stimulates the release of fullness hormones like GLP-1 and peptide YY. In contrast, liquid calories pass through the stomach quickly and often fail to register with the brain, leading to a "stacking effect" where individuals consume extra calories without feeling full.

— Since taking a GLP-1 agonist (Reta) already binds to GLP-1 receptors, it seems that feeling satiated off a medium calorie protein shake helps hit numbers better than feeling full on half a meal that provides less macros.

2: Blood Sugar and Nutrition: Whole foods contain fiber and intact cellular structures that slow nutrient absorption, preventing the rapid insulin spikes and crashes associated with liquid diets.

— If Reta stimulates insulin release when glucose is high while suppressing inappropriate glucose production in the liver, while also slowing gastric emptying, does that render that point mostly irrelevant as well?

I understand that there a vital micronutrients and vitamins that you can’t get in your diet from only consuming various shakes and fruit smoothies, and I’m definitely not suggesting that an all liquid diet would be a good idea due to short and long term GI issues.

My real question is, with proper macro/micro nutrient supplements and fiber support, would it be harmful or regressive for one seeking to lose weight and build muscle on a diet composed of 60-70% liquid intake? If the main concerns are accidental increased caloric intake, lower satiety, and blood sugar imbalances, wouldn’t taking a triple agonist pep like Reta negate those affects?

Any insight or criticism to this thought is greatly appreciated.

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Honestly, I don't think it's a problem. There are days when nearly everything I consume is in liquid form.

If I were you, I'd get bloodwork done to look for any micronutrient gaps. My lipid panel came back great, though my fatty acid balance is a bit to moderately off. I also turned out to be low on B6. So I've started taking a multivitamin and fish oil, and I'll get retested sometime around Christmas.
 
Each day I drink a protein shake that has 70 grams in it. Without it, hitting 200g of protein per day just isn't possible for me.
 
For me, protein powder supplements come with a couple of major downsides:

1) it triggers an insulin spike (I'm in ketosis)

2) there are other undisclosed ingredients, and heavy metals in particular — from what I've seen in most tests, the majority of proteins contain heavy metals

Bars: I haven't come across any that are actually good (whether judged by taste, ingredients, or price)
 
Given how much protein matters, there should be nothing wrong with adding high protein shakes when you need them. Because GLPs suppress appetite to such a degree, hitting your protein and hydration targets without supplementation can be really hard. That said, shakes and clear protein drinks shouldn't become your primary protein source.
 
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