One of the most difficult barriers dieters face are folks who try to sabotage their weight loss efforts. These are the folks who will shove an over-sized piece of cake in your face at a party or insist on having fried food at every meal. Every dieter faces them; your best defense is to be prepared.

Those sweet little ones can be a dieter's worst nightmare! Yelling for candy at the check-out aisle or insisting on eating chicken nuggets at every meal. Oftentimes you end up giving into their whining for processed foods and end up becoming the garbage disposal for their leftovers.

Your best defense: Both adults (dieting or not) and kids should be eating fruits, veggies, whole grains, lean meats and low-fat dairy foods. There are many deliciously healthy recipes that everyone can enjoy; get the kids in the kitchen to help choose and prepare healthy recipes and the whole family will benefit.

There's always one office pal who brings in the basket of baked goodies, insisting on watching you eat it. Then there are office-mates who go in groups to pick up the latest fancy coffee drinks, some with no less than 350 calories a pop. And if you try and explain that you’re watching your weight—that's the center of conversation for the next 2 weeks.

Your best defense: Stick to your guns (and your plan)-- overcoming office buddies is all about mind over matter.

Some friends let jealously get in the way. Although they've been supportive when you were having a bad day, they can't stand the fact that you're losing weight and becoming healthier. They insist on lunching at the fattiest restaurants in town and guilt you into splitting a huge appetizer or dessert.

Your best defense: Get them to join in on your weight loss efforts or consider dropping them along with the weight to become emotionally and physically healthier.

You love your spouse, but they can just be mindless when it comes to your weight loss efforts. Instead of the gallon of nonfat milk and whole grain cereal on your shopping list, they come home with bags filled with whole fat milk, sugary cereals and everything else you're trying to keep out of sight.

Your best defense: Team up with your spouse and get healthier together.

I love my grandma, but she's always telling me to eat more and to put on more lipstick (not necessarily in that order), shoving chocolate kisses in my mouth every 10 minutes. And if your grandma's cooking anything like mine, you just can’t resist her high-fat signature dish.

Your best defense: Keep your relationship with grandma to phone calls and video chats while trying to lose weight. And when you do share a meal together, split a serving of grandma's best dish with a relative.

Toby Amidor, MS, RD, CDN, is a registered dietitian and consultant who specializes in food safety and culinary nutrition. See Toby's full bio »