Protein and GLP-1s: How to Hit Your Daily Target

When you lose weight via a caloric deficit, you’ll generally average a ratio of 25% lean mass loss and 75% non-lean mass loss. It’s slightly more complicated than 25% muscle, 75% fat, but for the sake of convenience, we’re just going to say that’s what it is.

Preserving muscle during weight loss is essentially all upside: if you’re older, it helps protect against falls and other forms of fragility, it also increases quality of life in general, physical appearance (especially for males) and helps burn additional calories. This last point is a bit complicated, because exercise (resistance training is my recommendation) appears to actually decrease your resting metabolic rate (RMR), but it’s offset by the increased caloric demands of training.

There are two strategies we employ to reduce our lean mass loss: increasing our protein intake and resistance training. Today, I’m going to be talking about the former: you don’t need to do any resistance training, but even a little goes a long way. This guide assumes you’ll be training at least semi-regularly, but everything we’ll talk about is applicable even if you’re not training.

A primer on prioritizing high protein foods

It’s super basic, but even those with advanced knowledge of nutrition can have blind spots. Assuming you’re new to all of this: a lot of animal products are high in protein, especially lean meats, such as chicken breast, some fish, lean beef cuts and so on. I’m a vegan for ethical reasons, but it’s not the time for me to preach: all I will say is that you might want to consider adding some seafoods like oysters, mussels and sardines to your diet. Those animals are barely sentient and don’t feel much pain, plus their nutritional profiles are solid (omega 3s are also important). If you’re a vegan, soy should be your primary protein source: not all protein sources are created equal, and it is true that generally speaking, non-animal product protein is a little less effective, but soy is fantastic. Hard tofu does quite well head-to-head against a lot of animal protein sources.

There are two problems you can face regarding your protein intake: not getting adequate amounts because you’re falling short of your caloric goal or because your macronutrient partitioning means that when you do hit your caloric goal, you’re behind on protein. We’ll address these problems individually, but first: let’s talk about what number you need to aim for.

How much protein you’ll need

I’m going to keep it simple: your goal should be 1.6g per kilogram of bodyweight. Do you weigh 100 kilos? You need 160 grams of protein. Take whatever your weight is, multiply it by 1.6 and that’s your target. Yes, this even applies if you’re strength training every single day with a lot of intensity. Menno Henselmans has a fantastic article about optimal protein intake that you can read if you want to know more. Note that this is a target, not a budget: unless you have advanced kidney disease, more isn’t a bad thing.

I recommend utilizing the NIH’s body weight planner to calculate your calorie target. I cannot take most government initiatives regarding health seriously, but Kevin Hall is behind the planner and he’s dialed it in better than any rival calculator. It isn’t perfect, but given the information we have available, it’ll give you the most accurate answer you can get. You should have a calorie target too: can you lose weight without tracking anything on GLP-1s? Absolutely, but in terms of effort to reward ratio, I must insist you track calories.

The three protein problems with GLP-1s

Assuming you know your caloric target and your protein target, there are three combinations of problems you can have:

1. Not reaching your caloric target, but if you did, your macronutrient ratios would mean you hit your protein target.
2. Reaching your caloric target, but your macronutrient ratio means you didn’t hit your protein target.
3. Not reaching your caloric target, and even if you did, your macronutrient ratios would mean you wouldn’t hit your protein target.

I’ve ordered these in terms of severity: with the first being the least problematic. My advice is going to be somewhat similar in all cases, but I’ll break it down nonetheless.

#1 – Calorie target not reached, good protein ratio

You need to eat more. Okay, you already know that, but how? This can be a common issue for people who skip breakfast: one of the best interventions is eating as soon as you get up, even though you don’t feel like it. It sucks, yes – but remember that in this instance, protein is your medicine, and you should treat it as such. You don’t want to eat early, I don’t want to brush my teeth: food isn’t about pleasure, it’s about being healthy, and even if we start with a small meal to get things started, it creates a routine that we can build upon. Note that “breakfast” isn’t a binary either; don’t let perfect be the enemy of good; even if you’re eating 2 hours after waking up instead of your usual 4, that’s a win. You likely have a mental model of what times you typically eat at: try to close the gap and squeeze in an extra meal. Even a protein snack of some description is better than nothing. Plenty of protein bars out there offer around 30g of protein for 90g of food: they taste okay, but the convenience is the main selling point.

If you’ve been tracking for sufficiently long enough, you’ll have a library of good days and bad days – go through your logs and ask yourself: “what was distinct about the good days?”. It was likely the combination of foods you ate, and it’s typically as simple as “I managed to eat more calories with this combination of foods because it took me longer to get full and I like the taste”. Prioritize those foods in the future.

I’ve also saved the best – and likely the most obvious piece of advice – for last: take a lower dose of whatever GLP-1 RA you’re on. Be sure to let your doctor know, though.

#2 – Calorie target reached, bad protein ratio

“Bad protein ratio” can mean anything from 1.5g/kg through to 0.5g/kg: be honest with how far away you are on a day-to-day basis, but you also have to factor in the rate at which you’re planning to lose weight. Is your calorie target so low that you’d have to essentially only eat chicken breast every single meal to reach the 1.6g/kg target? I think it’s prudent for me to suggest a maximum theoretical ratio of calories to protein that you should be targeting: 90g of protein for every 1,000 calories seems about the limit before the intervention is more total calories, not a better macronutrient ratio.

As above, if you have been tracking your daily intake, you have a record of good days and bad days: do some critical analysis on what made good days good and bad days bad. We’re going to try and prioritize the meals and eating structures of the good days and not so much the bad days. You might also want to do a deeper dive on food selection: there may be a single thing that’s really tripping you up, and you’re budgeting far too many calories toward a food that’s stacked with fat and carbs. Don’t be afraid to look at a long list of foods and their protein to calorie ratios either.

Try to build a framework of base high protein products you can add other foods to. When I’m really behaving, I’ll have 200g of hard tofu (45g of protein) and say, 200 calories of something else. Sometimes it’s sweet potato, sometimes it’s cauliflower and walnuts, sometimes it’s a peas and a banana. The tofu isn’t fun, but again, food is medicine, and the GLP-1 RA I’m taking removes my interest in consuming food for pleasure.

My final piece of advice is to consider a daily protein shake, ideally as close to your workout as possible (before or after is your choice). Protein shakes have a small downside of hyperaminoacidemia (saturating your blood with amino acids, which is why we’re consuming protein in the first place) occurring for a shorter period of time because they’re so easily digested, but I have a pet theory that because GLP-1 RAs delay gastric emptying, they might be more viable as a daily protein source. In fact, I’d be super interested in knowing if this is true (which it almost certainly is), but more importantly, how true it is. Does it increase the muscle full effect for just a few minutes, an hour or even longer? I don’t know what the answer is, but it has made me reconsider protein shakes for my own diet (I currently do not use them).

#3 – Calorie target not reached, bad protein ratio

As above, this could mean anything from being 95% of the way there to miles off. I considered rewriting the points above, but since almost all of it applies, it’s better to just read #1 and #2. The tl;dr is taking a lower dose, eating more frequently and doing an audit on what meals have worked well and what ones have caused you to struggle.

A few final thoughts

I know from my own experience, and through discussions I’ve had with others, it can be easy to be exceptionally motivated for brief periods of time and often, that can translate into quite an extreme caloric deficit. I never quite knew how long my discipline would last, and so I likely had a caloric target that I wouldn’t recommend for someone else – bad idea. It’s really important to remember that with GLP-1 RAs, it’s unlikely you’ll regain the weight – just so long as you keep taking the medicine. You should be completely comfortable with an extra month or two to reach your goal weight, because this time, it’s permanent. If you’d like more information on protein, there’s a great lecture here on the Barbell Medicine YouTube channel. It covers carbs and fats too, and one or two points might be slightly off from recent data (it’s close to a decade old at this point), but it’s a fantastic source of information nonetheless.

Thanks for reading: I hope this helps you toward hitting your daily protein targets while on a GLP-1 RA.