Oxyshred Lean Protein Bars

Most of the choice in this aisle comes down to whether you need the lean part at all, so these are the questions our naturopaths ask in store.

A good fit if

• You're eating fewer calories to lose fat and still training. That's exactly what this evidence covers.
• Food alone isn't getting you close to your daily protein total
• You track carbohydrate or fat per serve closely enough that a few grams make a difference
• You'd rather choose on protein per serve than on what the front of the tub promises

Check with us first if

• You take medicine for blood sugar and the blend contains chromium picolinate. Chromium can affect how your body handles insulin, and that combination hasn't been checked for these products yet.
• You take prescription medicine and the blend contains green tea or caffeine. Australia's permitted ingredients list warns that caffeine interacts with the liver enzyme CYP1A2, so count what your coffee adds too.
• You have kidney problems. The reassuring evidence only covers healthy adults, so your protein intake is one to discuss with your doctor.
• Lactose doesn't agree with you. Whey protein taken by mouth has to contain lactose, and a plant-based blend avoids that.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.

• Whey protein isolate base. Best known for: The usual lean base: filtering raises the protein content and removes most of the lactose, fat and carbohydrate. Absorption: Sold as a fast protein, though we haven't cited research on how quickly it's digested. Typical use: Everyday use while eating less. The evidence rests on your total protein, not the grade you use to reach it.
• Whey protein concentrate base. Best known for: A lower protein content, and it keeps more of the lactose and fat a lean profile cuts. Absorption: The same evidence applies, because it's about protein content, not how the whey was filtered. Typical use: Fine for hitting a daily total, less so on a strict low-carb plan.
• Casein base. Best known for: A slow dairy protein, usually sold for overnight use rather than fat loss. Absorption: Slow digestion is well described for casein, but we haven't cited research on it here. Typical use: A night-time serve. Nothing here tests casein against whey for body composition.
• Plant base (pea, soy or rice, usually blended). Best known for: The dairy-free option, and usually low in fat without anything being filtered out. Absorption: Not measured here. Protein quality varies by source, which is why most plant tubs blend two. Typical use: If you avoid dairy. Check the allergen statement, because soy must be declared and blends get reformulated.
• Fat-metaboliser blend (protein plus chromium, carnitine, CLA or green tea extract). Best known for: A protein base with extras added, marketed for fat metabolism or appetite. Absorption: Beside the point, because no verified trial we reviewed tests any of those extras. Typical use: Judge it on the protein. If the tub contains green tea or caffeine, your daily caffeine total is what matters.

Reference values. We're not giving one here. We didn't find the NHMRC protein reference value in the research for this page, and we'd rather give no number than one we can't link to. What you need depends on your weight, your age and how hard you're training and cutting.

Typical supplemental range. Four trials give the ranges, and they're daily totals from all food rather than scoop sizes. In a big calorie deficit with six training sessions a week, 2.4 grams of protein per kilogram of body weight beat 1.2 grams over four weeks. Across 49 training trials combined, gains stopped increasing at about 1.6 grams per kilogram. Lean athletes cutting hard may need more, around 2.3 to 3.1 grams per kilogram of fat-free mass, while weight loss diets in general are quoted at 1.2 to 1.6 grams per kilogram.

Upper level. The evidence behind this page doesn't establish an upper limit for total protein in your diet. The two caps that do apply are on the extras, and they're set out in the Australian rules section on this page.

Worth knowing. A powder tops up your day's protein. It doesn't replace the meals or the training that give your body a reason to use it. What you need depends on your age, diet and health, so talk to one of our naturopaths.

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• You're pregnant or breastfeeding and the blend contains green tea extract or caffeine. More than 200 mg of caffeine a day is not recommended.
• The blend contains a meaningful dose of green tea extract. A warning about rare liver harm is required: stop if you notice yellowing skin or eyes, dark urine, unusual tiredness, nausea, loss of appetite, stomach pain or itching.
• You take medicines processed by the liver enzyme CYP1A2 and the blend contains caffeine. Above 80 mg of caffeine a day, the label must tell you to check with a health professional.
• You take glucose-lowering medication and the blend contains chromium picolinate. This has been flagged for checking rather than settled.
• Chromium picolinate. A listed medicine can provide no more than 50 micrograms of organic chromium a day.
• You're lactose intolerant. Whey protein must contain lactose when taken by mouth; a plant base avoids it.
• You have kidney disease. The pooled evidence showing no harm covers healthy adults only.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.