Does eating gluten-free help if you don't have coeliac disease?
For healthy people without an established condition, there is no evidence that eating gluten-free provides any benefit, and it carries nutritional risks. If you experience symptoms after eating wheat, have that assessed by a doctor before changing your diet.
Worldwide, around 10% of adults report being sensitive to gluten. Yet when this is put to a controlled test, only 16 to 30% of them turn out to have gluten as the actual cause of their symptoms. The rest probably have something else going on.
What, then? Besides gluten, wheat contains fermentable carbohydrates and other substances that can irritate the gut. When someone experiences fewer symptoms on a gluten-free diet, there is a real chance that those substances, and not gluten itself, were the problem. That makes 'wheat sensitivity' a more accurate description than 'gluten sensitivity'.
A double-blind study in 83 people who considered themselves gluten-sensitive reveals a striking pattern. The group that thought they were eating gluten but were not had clearly more symptoms than the group that unknowingly consumed gluten. Eating gluten alone, without knowing you were eating it, did not produce more symptoms than a placebo. Expectation therefore plays a major role -- a so-called nocebo effect.
For people with a diagnosed wheat sensitivity, established after ruling out coeliac disease and wheat allergy via a controlled test, a gluten-free diet can reduce symptoms. However, no reliable blood test exists. Making the diagnosis without such a formal test is uncertain.
For healthy people without an established condition, a gluten-free diet offers no proven benefit. Gluten-free products are also often lower in fibre, vitamins and minerals, and are more expensive. For people with gastrointestinal complaints who suspect they are sensitive to wheat, it is more sensible to have that assessed by a doctor than to start eating gluten-free on their own initiative.
This answer draws on several review studies and one double-blind randomised study in 83 participants. The review studies are consistent in their findings on the nocebo effect, the role of other wheat components, and the absence of biomarkers. The randomised study is the only one that could directly test cause and effect; the rest show associations but cannot prove causation. The diagnosis of 'non-coeliac wheat sensitivity' still has no reliable diagnostic test, which makes the entire field difficult to study.
Does eating less help you live longer?
In laboratory animals the effect on lifespan is well established, but in healthy humans direct evidence is lacking. A moderate and sustainable eating pattern is wiser than extreme restriction; discuss major changes to your diet with a dietitian or doctor.
Does the order in which you eat food and vegetables during a meal matter?
Eating vegetables and/or protein first and carbohydrates last demonstrably blunts the post-meal blood sugar spike, even in healthy people. It is a small adjustment with no downsides that you can simply try out.
Does extra protein help with losing weight without losing muscle?
Extra protein helps preserve muscle mass while losing weight, but works best in combination with resistance training. Aim for 1.6-2.4 g per kilogram of body weight per day, and make sure to train alongside it.
Is eating organic really healthier?
Eating organic probably does not give you better nutritional value, but it does lower your exposure to pesticide residues and to antibiotic-resistant bacteria through meat. For pregnant women and young children, that is the strongest concrete argument.
Is a low-carbohydrate or ketogenic diet good for longevity?
A ketogenic diet can help with weight problems and metabolic disorders, but for people who simply want to live longer and healthier, no proven advantages over a varied diet have been demonstrated. Those who exercise intensively may even be at a disadvantage.
Does eating a high-fibre diet help against constipation as you get older?
Eating more fibre helps against constipation in older adults, but the overall dietary pattern counts at least as much as fibre grams alone. Always drink sufficient water when taking fibre supplements, and consult your doctor if you use medications or have difficulty drinking enough.