Ask almost anyone what matters nutritionally when you are eating less and the answer comes back protein. It is the right answer, and we have written about it before. But it arrives first so reliably that it crowds out something with a stronger evidence base behind it, and something that falls away faster when portions shrink.
So this piece runs in reverse. Fibre first. Then the short list of supplements worth considering when intake drops. Then sleep and stress. Protein last, and in food rather than arithmetic.
Fibre, and why it goes first
The number is bigger than most people expect.
A 2023 meta-analysis in Clinical Nutrition pooled 64 prospective studies covering 3,512,828 people. Compared with the lowest intakes, the highest fibre intakes were associated with 23 percent lower all-cause mortality, 26 percent lower cardiovascular mortality, and 22 percent lower cancer mortality.
For a nutrient most people file under regularity, that is a substantial finding.
Fibre also predicts weight loss, apparently regardless of how much you eat.
This gets almost no airtime. A secondary analysis of the POUNDS Lost trial followed 345 adults with overweight or obesity across four different energy-restricted diets for six months. When the researchers modelled which dietary factors actually predicted weight loss, fibre intake was the single most influential predictor, ahead of macronutrient composition, and independently of total energy intake. Average weight loss across the group was 7.3 kg.
Fibre also independently predicted whether people stuck to the diet at all, which may be most of the mechanism. Fibre-rich food is harder to overeat and keeps you full longer, so adherence improves, so the deficit holds.
One caveat for accuracy: fibre was not the randomised variable, so “independent of calories” means statistically adjusted rather than causally isolated. A strong signal within a well-run trial rather than proof.
Australians do not get close to the target, and eating less makes it worse.
Analysis of the National Nutrition and Physical Activity Survey found median fibre intake among Australian adults was 20.7 grams a day. The NHMRC’s Adequate Intake is 25 grams for women and 30 for men. The Suggested Dietary Target, set specifically for reducing chronic disease risk, is 28 grams for women and 38 for men.
More than seven in ten adults fall below the Adequate Intake. Fewer than one in five reach the target.
And the finding that matters most here: people with higher total energy intake were more likely to meet the fibre target. Fibre travels with food volume. Halve the food and the fibre halves with it, without any decision being made.
Which is where psyllium earns its place.
We are not going to pretend a supplement inherits the mortality data. In that meta-analysis insoluble fibre outperformed soluble, and the benefit came from wholegrains, vegetables, nuts and seeds. Psyllium is an isolated soluble fibre, and nobody has run a trial showing a fibre supplement extends life.
That objection is a little academic when the practical situation is this: most Australians are eight to eighteen grams short before they start, eating less pushes them further behind, and food alone is a hard way to close that gap on a suppressed appetite.
Psyllium is cheap, tasteless enough to disappear into a drink, and has solid evidence in its own right for lowering LDL cholesterol, slowing glucose absorption, easing constipation and increasing fullness. Five to ten grams a day closes a meaningful part of the gap without requiring you to eat more food than you can face.
Two cautions. Bulk-forming fibre needs fluid to work and can worsen constipation without it. And anyone with significantly delayed gastric emptying should raise it with their prescriber before adding a bulking agent. Start low, build up over a week or two, and drink to it.
The short list worth considering when intake drops
At Anova we would rather name four things with reasons than fifteen without. The framing here is adequacy, not optimisation. The question is not what might make a healthy person marginally better, it is what falls short when someone eats substantially less than they used to.
Creatine has the strongest evidence here for preserving muscle during weight loss, alongside resistance training. Cheap, extremely well studied, and monohydrate is the form with the evidence. It works on daily consistency rather than timing, so it belongs wherever you will actually remember it. It supports rather than replaces the training, which is the real intervention, covered in harder, not longer.
Vitamin D matters in Australia more than the sunshine suggests, particularly in southern states through winter, for indoor workers, and for anyone who covers up. Worth testing rather than guessing, which is a GP conversation.
B12 and iron are the two most likely genuine shortfalls, and the risk is higher for vegetarians and for anyone whose intake has dropped sharply. Testable rather than assumable.
Calcium with vitamin D is worth raising because rapid weight loss reduces bone density through mechanical unloading. More relevant for postmenopausal women and older adults than for everyone.
A basic multivitamin sits in a defensible middle position: modest evidence, low cost, reasonable insurance when the diet has shrunk. What it is not is a substitute for food.
Sleep and stress, what to look for
Sleep gets worse for a lot of people during weight loss, and stress is usually already in the room. This is the category with the largest gap between confidence and data, so it is worth knowing what actually has evidence behind it.
Start with the free things, because they work better than the paid ones.
A consistent wake time matters more than a consistent bedtime. The body clock anchors to when light hits your eyes in the morning, not to when you turn the lamp off, so getting up at roughly the same time every day, including weekends, does more than almost anything else available.
Get outside within an hour of waking, for ten to twenty minutes if you can. Outdoor light on an overcast morning is still many times brighter than indoor lighting, and that signal is what sets the timing of melatonin release roughly fourteen to sixteen hours later. Then dim things down in the evening. The goal is a gradient across the day, bright in the morning, dim at night.
One technique worth borrowing from insomnia therapy. If you are lying awake for more than about twenty minutes, get up. Go to another room, keep the lights low, do something undemanding, and go back when you feel sleepy. It sounds counterproductive and it is the most consistently effective single thing in the evidence base. The logic is that time spent awake and frustrated in bed teaches the brain that bed is a place for being awake and frustrated. Getting up breaks that association. Do it as often as needed.
On supplements, the list is short.
Magnesium has the best evidence of the over-the-counter options, and it is modest rather than compelling, with glycinate the form usually studied for sleep. L-theanine has reasonable evidence for subjective calm. Glycine has a small supporting literature. None of these are dramatic, and none will outperform fixing the timing.
Melatonin is a prescription medicine in Australia, and this catches people out constantly. It is Schedule 4 for most people. The one exception is a 2 mg prolonged-release formulation, available from a pharmacist without a prescription for short-term insomnia in adults aged 55 and over. If you have read an overseas article recommending it, or seen it sold openly in an American pharmacy, that is not the situation here.
This matters practically. In September 2025 the TGA issued a safety alert after testing imported, unregistered melatonin products bought through overseas websites. Some contained up to 400 percent more melatonin than the label stated. Others contained less, or none at all. A legitimate product sold in Australia carries an AUST L or AUST R number. No number means no Australian oversight, which for a hormone is a meaningful gap.
If sleep has been bad for more than a few weeks, that is a GP conversation rather than a supermarket one.
Protein, without the arithmetic
The standard advice is 1.6 to 2.2 grams per kilogram of goal body weight, which is correct and leaves you doing sums at the fridge. Here is what it looks like as food. A reasonable target for most adults losing weight lands between 100 and 140 grams a day.
An omnivore day
- Two eggs on wholegrain toast, around 20 grams
- 200g tub of Greek yoghurt, around 18 grams
- A 95g tin of tuna through a salad at lunch, around 22 grams
- A palm-sized piece of chicken breast at dinner, around 30 grams
- A glass of milk and a handful of almonds across the day, around 14 grams
Roughly 105 grams.
A vegetarian day, matched serve for serve
- 170g firm tofu scrambled with turmeric and spring onion on wholegrain toast, around 20 grams
- 250g tub of high-protein soy yoghurt with berries, around 16 to 18 grams depending on brand
- A chickpea and white bean salad with feta, lemon and parsley, around 22 grams
- 150g tempeh, marinated and roasted, or a lentil and spinach dhal, around 28 grams
- Soy milk and a handful of almonds across the day, around 13 grams
Roughly 100 grams. That version leans heavily on soy across four of the five items, which is fine for most people. Anyone who would rather not can run the chickpea and lentil route instead and land in much the same place.
On milk specifically: soy is the only plant milk that meaningfully replaces dairy for protein. An audit of 129 plant milks on the Australian market found soy sitting close to cow’s milk, while almond came in at 0.7 grams per 100ml, oat at 1.0, coconut at 0.3 and rice at 0.2, against 3.6 for dairy. A few brands now sell protein-fortified almond and oat, worth checking the panel for, but the standard product is not a protein source.
Legumes are where the vegetarian version gets easy rather than worthy. A cup of lentils blended into a bolognese, through a curry, or folded into a taco filling with cumin and lime disappears entirely and adds close to twenty grams. A better use of them than a bowl of plain lentils nobody wants to eat.
Now the problem with both lists.
Read them again and imagine eating all of that mid-week on a suppressed appetite, when dinner already feels like an obligation. Five substantial eating occasions is a large ask, and anyone who has been through the flat days knows the tin of tuna is not happening.
So treat the lists as the target, not the instruction. On the days you cannot get near them, there is a better option than writing the day off.
How a smoothie can help
We have written about why some foods never fill you up: energy that arrives fast, in a low-volume form requiring no chewing, slips past the fullness machinery almost entirely. That is what makes engineered snack food so hard to stop eating.
The same physics runs in reverse when the problem is getting nutrition in rather than keeping it out.
A blended drink is dense, needs no chewing, and takes up little stomach volume for what it delivers. A problem when it is a milkshake, an advantage when you have loaded it deliberately. Yoghurt or soy yoghurt, a scoop of protein powder, a teaspoon or two of psyllium, a tablespoon of nut butter, some frozen berries.
That is thirty to forty grams of protein and several grams of fibre in something you can finish when a plate of food would defeat you. Your stomach barely registers it as a meal, which on those days is exactly the point.
Two provisos so this does not become the whole diet. Whole food is better whenever you can manage it, because chewing, volume and food matrix all do real work. And a smoothie is for the days appetite is against you, not a replacement for learning to eat normally, which is the actual long-term skill.
If you are starting psyllium, protein powder and creatine at once, add them one at a time over a fortnight. Otherwise if something disagrees with you, you will have no idea which one it was.
What we would actually do
Eat fibre from food and treat psyllium as the gap-filler it is, not the strategy. Get vitamin D, B12 and iron tested rather than guessed. Take creatine if you are lifting, which you should be. Fix the sleep timing before buying anything for it, and check the Australian regulatory status before ordering from overseas. Build protein from ordinary food, and blend it when appetite is against you.
And take the whole list to a GP or pharmacist before starting, particularly if you are on medication. Supplements interact, and a shrinking diet is a medical circumstance rather than a lifestyle one.
The reason fibre goes first here is not that it beats protein. It is that protein has an advocate in every conversation and fibre does not, and the nutrient nobody is arguing for is usually the one quietly going missing.
This article discusses general findings from nutrition research and Australian dietary intake data. It is general information, not personalised dietary or medical advice, and is not a recommendation to start any supplement. Supplements can interact with prescribed medication. Decisions about supplementation, particularly while on weight management medication, belong with your GP, pharmacist or dietitian. If sleep or stress has been a persistent problem, please speak with your GP.