What is the recommended serve for schnitzel, steak, pasta or vegetables? The results may surprise you.

A proposal to reduce the size of Adelaide pub schnitzels by waste reduction organisation Kesab drew widespread criticism on Monday.

Patrons said it was their right to consume 500-gram crumbed steaks, but dietician Julie Gilbert said the calorie count alone should put people off.

"It's actually the same as eating 10 slices of bread in one sitting," Ms Gilbert told 891 ABC Adelaide's Mornings program.

"We think the challenge of eating a 500g schnitty is something we should be aiming for, not realising that is a lot of food and will require around five hours of walking to burn that off."

What is a recommended food portion?

Ms Gilbert said the recommended size for one portion of meat was 100 grams.

"A larger male may go up to 150 grams, which would be [approximately] their palm size."

Our growing waistlines In 1995 ABS body mass index figures revealed 56.3 per cent of Australian adults were overweight or obese.

In 1995 ABS body mass index figures revealed 56.3 per cent of Australian adults were overweight or obese. 2011-12 figures showed that figure had jumped to 63.4 per cent.

2011-12 figures showed that figure had jumped to 63.4 per cent. Adults deemed to be obese rose from 19 to 27 per cent during the same period.

Adults deemed to be obese rose from 19 to 27 per cent during the same period. OECD figures in 2013 showed Australia ranked fourth in countries with high obesity rates, behind the US, Mexico and Hungary.

She said diners should be aiming to fill half of their plates with vegetables.

"That's not including your starchy vegetables like potatoes or sweet potato."

Ms Gilbert said the measurement of vegetables should be approximately one to one-and-a-half cups.

"That would be like getting your fist and clenching it."

The recommended serving size for pasta was also a lot smaller than most expected, Ms Gilbert added.

"It's actually half a cup — and that is cooked," she said.

A recommended serving size for fruit was 150 grams, cheese should be the same size as a matchbox, and a standard coffee would fulfil one recommended dairy serve.

The age of 'portion distortion'

Ms Gilbert said the increase in food portions over the past 30 years was astounding.

"We are often driven by value for money," she said.

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"That may be OK if we were using eating out as a special occasion, but since we are now eating out more regularly, this is where it is becoming a problem."

Ms Gilbert said the daily recommended serving sizes of food groups were:

Fruit — two servings

Fruit — two servings Vegetables — five

Vegetables — five Dairy — three

Dairy — three Grains and cereals — between three to five (depending on activity)

Grains and cereals — between three to five (depending on activity) Meat — two to three serves

"In Australia we definitely exceed the recommended portions, so when people say we need to be on a high-protein diet, the majority of us are already achieving that," she said.

Meanwhile, talkback callers offered some novel responses to the proposal to reduce the size of the Adelaide schnitty and pub portions in general.

"Whenever we buy a meal my wife and I order one serve and two plates. Plenty for us," Robert Pattison from Hackham said.

"Restaurants should realise prawns is plural," another listener said via SMS.

"Pubs seem to assume every vegetarian is doing it to lose weight, but the lack of meat means I need more not less food," Sam said.

"The Aldgate pub used to do a schnitty called the Parmageddon," Todd added.

"Hands off my big schnitzel Kesab," Robert from the truck said.

"I have never not finished my schnitzel or my wife's schnitzel," he added.