Genes are largely to blame for bulging waistlines, a study has found.
While diet plays a key role in obesity, some people are programmed to get fat easily, research from the US suggests.
Although the work focused on mice, it is believed to be just as relevant to humans.
Lead scientist Dr Brian Parks, from the University of California at Los Angeles (UCLA), said: "Our research demonstrates that body-fat responses to high-fat, high-sugar diets have a very strong genetic component, and we have identified several genetic factors potentially regulating these responses.
"We found that obesity has similar genetic signatures in mice and humans, indicating the mice are a highly relevant model system to study obesity. Overall, our work has broad implications concerning the genetic nature of obesity and weight gain."
Dramatic increases in obesity over the past few decades have been linked to high-calorie sugar and fat-rich diets as well as sedentary "couch potato" lifestyles.
But the new research indicates that body-fat responses to food are to a large extent hard-wired in to our DNA.
Over the course of the two-year study, the UCLA team looked at the effect of high-calorie diets on more than 100 strains of laboratory mice.
The scientists located 11 regions of the genetic code associated with obesity and fat gain due to diet. Several of these overlapped with genes identified in human studies.
"We measured the change in fat dynamically at five different points following a high-fat, high-sugar feeding, providing strong evidence for a genetically controlled body-fat set-point," said Dr Parks.
"Our use of inbred mice strains also enabled detailed analysis of the relationship between obesity traits, gene expression, intestinal flora and diet."
Dietary responses varied greatly across strains, according to the findings reported in the online edition of the journal Cell Metabolism.
Increases in body fat as a proportion of weight ranged from zero to 600%.
Most mice strains responded during the first four weeks of a high-calorie diet and did not accumulate more fat during the remainder of the study. This suggests they reached a natural upper threshold limit after which continued fat gain was resisted by genetic mechanisms.
"We observed high heritability of about 80% for body-fat percentage across the study timeline," said co-author Professor Jake Lusis, also from UCLA.
"Changes in body-fat percentage after high-fat, high-sugar feeding were also highly heritable, suggesting that dietary responses are strongly controlled by genetics."
The findings are consistent with generational patterns of body mass index and obesity seen in humans, said the researchers.
"Our results emphasise the importance of gene-by-environment interactions, with important implications for an understanding of the overall genetic architecture of obesity," said Prof Lusis said.
"In particular, it will be of interest to examine behavioural and neurological differences among the strains as they relate to obesity traits."
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The Inner Aisles
Grocery stores are designed in such a way to have the essential ingredients such as dairy and produce on <a href="http://www.curbly.com/users/diy-maven/posts/2289-top-20-ways-to-save-money-at-the-grocery-store" target="_hplink">opposite ends of the store</a>. This forces most shoppers to pass through all the aisles, often times picking up items they don't need. Try to skip the middle of the store and stick to only the items you need.
You might be used to a particular brand of cereal or sugar, but the generic options are usually cheaper. The grocery store brands often use name-brand products with their own labels on it; and they offer it at a better price. Just check the ingredients to be sure you are getting the same product.
While buying toiletries at the supermarket may be easy, you're paying a price for that convenience. Save those items for the pharmacy, where they are usually cheaper.
Since we tend to look at items that are at our eye level, grocery stores know to place the <a href="http://www.bankrate.com/brm/news/cheap/331Ways/DailyLife/groceries.asp " target="_hplink">more expensive items on the shelves we see first</a>. When shopping, look at the higher and lower shelves for cheaper items.
Don't buy the pre-made foods such as potato salad at the store, when you can purchase the ingredients and make it for a fraction of the price at home. And it'll taste much better fresh too.
Shopping With Children
While sometimes we can't avoid shopping with children, it's best to try to buy your groceries when they're not around. Children will often want to buy food items that you don't need, and it isn't always easy to say no.
Just like with pre-packaged lettuce and pre-cut fruit, grated cheese costs you extra for the convenience it brings you. But it's not that hard to grate your own cheese. With a less expensive block of cheese, and a cheap box grater, you can start saving money on this ingredient.
Shopping When Hungry
Many of us go to the grocery store after work and before dinner, which is when we start to get hungry. If you buy your groceries when hungry, you'll <a href="http://www.psychologytoday.com/blog/the-science-willpower/201107/the-neurobiology-dont-shop-when-youre-hungry" target="_hplink">purchase more than you need</a>. Try to get the shopping out of the way on the weekends, when you can shop on a full stomach.
Almost all supermarkets list the unit price of their items. It's wise to look at these as they make it easy to see which brand really gives you the best deal for your money. This way you can avoid being fooled by overly packaged items with little inside.
The Offender: Pre-Packaged Salad
Yes, it's convenient to have your lettuce in already-clean-and-trimmed plastic tubs, but it also costs nearly three times the price. If you buy your own head of lettuce, wash and trim it right away, and have it ready to use, you won't even notice the difference (and you'll save quite a few bucks a month).
No Shopping List
You might have an incredible memory, making it able to remember everything you need from the supermarket without having to write it down (an admirable and uncommon skill). And while writing a shopping list does help many of us remember what we need to get, more importantly, it keeps us from buying the things we don't need (if we stick to our list).
Many people opt for canned beans because they're too intimidated to <a href="http://www.huffingtonpost.com/2011/10/27/susies-beans_n_1062584.html" target="_hplink">cook their own</a>. But making a good pot of beans is really easy. So fear it no longer, and start saving some money by buying the bags of dried beans instead of cans. While the difference in price is not enough to break the bank, these little changes will add up.
If someone is getting paid to do a job that you could easily do yourself at home (like cutting up a mango) you're going to be paying for it.
You've heard it before, and you'll hear it again: eat the produce that's in season. Not only will it taste infinitely better, but it will save you serious money. Because it costs them less to produce fruit and veggies that are local and in season, it costs less for you to buy it.
Bottled water is a multi-million pound industry, and it's coming out of your pocket.
Fancy spice mixes can be a biggest waste of money since you can make your own spice mix with seasonings you most likely already have on hand (a large portion of most of the mixes being salt).
The Offender: Fresh Herbs
You're literally throwing money away by not starting your own herb garden. Fresh herbs cost a small fortune at the grocery store. Often times you can buy an entire plant for less than you can a few sprigs at the supermarket. And while not everyone has space for a garden, most people can fit at least a few pots somewhere in their home.
While experimenting with your cooking is a good idea, it's not always wise to buy those spices at your local grocery store. Taking the time to make a trip to an international market can save you a ton (almost 10 times in savings) on spices and specialty ingredients.
WATCH: How To Do Your Food Shopping
This item is a major culprit of wasting your money. Sometimes you can pay almost double the price just for the convenience of having individual microwaveable bags. But what you're really doing is paying more for inferior popcorn. Save money, pop your own, and enjoy the real flavor of freshly popped corn.