Protein Targets and the Lab Panel

“Eat more protein and get your bloods done” is the standard advice, and it is useless without numbers. Two 2026 reviews put numbers to it: a floor of 1.2 g protein for every kilogram you weigh, divided so each meal carries its share, plus a six-test laboratory panel.^[1][2] What follows is those figures and the one exclusion attached to them.

The protein targets

The per-meal figure matters more than people expect. Muscle protein synthesis responds to a threshold dose at a sitting rather than to a daily total, which is why the framework specifies both. On a drug that suppresses appetite, hitting a per-meal target across fewer, smaller meals is genuinely hard — and it is the practical reason protein tends to be the macronutrient that slips.

The laboratory panel

The proposed panel is short and specific: vitamin D, B12, iron studies, folate, zinc and thiamin.^[1]

Each is there for a reason connected to how these drugs work rather than to general wellness testing. Reduced intake and reduced dietary diversity affect all of them; nausea and vomiting affect thiamin acutely; and baseline inadequacy is already common in people with obesity before any drug is involved, which the reviews note explicitly.^[1][2]

What runs low in practice, with figures from a large dataset, is covered separately in eating too little on a GLP-1. This panel is the counterpart: not what falls, but what to measure.

Six tests. It is a short list precisely so that it gets done.

Energy floors

The same framework proposes pragmatic energy floors — a minimum daily intake below which micronutrient adequacy becomes very difficult regardless of what you choose to eat.^[1] That is the conceptual point worth taking even without a specific number: below a certain intake, no amount of good food selection compensates, because there is not enough food.

This is where the appetite suppression that makes the drug work becomes the thing to manage. Appetite is a poor guide to adequacy on these drugs by design, which is the argument for eating to a plan rather than to hunger.

Vitamin D, and why the number moves on its own

One panel value behaves in a way worth understanding before anyone reacts to it. In a randomized trial of 195 people, an eight-week low-calorie diet raised serum vitamin D by about 12 to 13 nmol/L in both women and men, with no supplement involved.^[3]

That mechanism explains the study’s most striking finding, and explains it away. Women who went on to lose more weight over the following year had lower vitamin D at the start — 54 nmol/L against 70 in women who regained. Read as a predictor, that says poor vitamin D status forecasts success, which makes no sense. Read as a fat compartment, it says those women had more fat to begin with, and more to lose.

The practical consequence is that a rising vitamin D level during weight loss is not evidence that anything is being done right, and a low one at the start is not necessarily a deficiency to correct. It is a measurement whose denominator is changing underneath it. Whether to supplement is a question for the clinician reading the whole panel, and this particular number should not drive it on its own.

The same trial found the additional rise with further weight loss only in women, which the authors report without explaining. We are not going to explain it either.

What kind of evidence this is

Both sources are narrative reviews proposing a framework, not randomized trials testing one. The protein targets are guideline-informed extrapolations into a new context rather than figures validated in people taking these drugs.

That is a real limitation and it does not make them useless. There is no trial establishing the right protein intake on a GLP-1, and there may never be one; in its absence, an explicit number derived from established nutrition guidance is more useful than “eat more protein”. Our lean mass article covers the outcome these targets are aimed at, and the one intervention with randomized support behind it: resistance training.

One thing these targets do not address: they assume the protein is available at the amount stated, and where it comes from changes how hard that is. If you eat little or no animal protein, the daily total matters more than it does otherwise and the per-meal response is weaker — see plant-based protein on a GLP-1 for what the trials measured. Creatine is the supplement most often suggested alongside a protein target; what the evidence supports for creatine on a GLP-1 is narrower than the marketing, and no trial has tested it in anyone taking these drugs.