mark liverman explains how it could help in the fight agnsort fight diabetes and obesity? new research shows drinking a cup of coffee can stimulate what is known as brown fats. the fat you warm by burning calories. dr. david agis is a cbs news medical contributor. >> normal fat stores energy, calories. brown fat has a lot of iron which is why it is brown around its purpose is to generate heat. is goal is to stimulate it. exercise stimulates it. good sleep. and now, we know caffeine or coffee can do the same. >> reporter: the study published in scientific reports is one of the first to be carried out in people. previous research shows drinking coffee may have many health benefits including a lower risk of diabetes, cardio vascular and death. don't drink more than three cupping of coffee a day. no coffee after 1:00 or 2:00. caffeine half-life is six hours. it will only be half the level , en ieep, il not be the deep restful sleep with caffeine on reer: research studying caffeine supplement to see if the effect on brown fat is similar. mark liverman, cbs news, new york. >>> e

mark liverman reports. >> reporter: two days of talks between the u.s. and mexico have yielded significant concessions but not enough to stop the white house from going ahead with a planned 5% tariff on all goods imported from mexico. >> it is a beautiful thing if you know how to use them properly. >> reporter: with time running out and opposition to the policy growing on capitol hill, president donald trump appeared on fox news to defend the administration's approach. >> there are senators and others and pelosi saying how horrible. what they are doing is hurting the deal. they should be saying we're with the president, we'll do whatever he wants to do and mexico would fold like an umbrella. now i have these people and there are some republicans, too, i think they should be ashamed of shelf sefs. >> the white house is using the threat of tariffs to get mexico to do the house ways and means committee said he will introduce a resolution of dis approval to block the tariffs saying common dearring u.s. trade policy to influence border security is an a becaus

marc liverman is live in new york city with how the deadly crash did spark a lot of fear for some people. mark. >> reporter: there is no question that it brought a lot of new yorkers back to less than 20 years ago talking about 9/11. so many unanswered questions in this crash that happened just a few hours ago. most of the scene is clear. emergency officials are saying that this was not an act of terror. seventh avenue back open. of course the investigation goes on. this is the building right there in the distance where it happened. it is still so foggy that you cannot even see the roof. this is what it looked like moments after it happened. >> smoke poured from the top of this building on seventh avenue where a helicopter made a hard landing. crews the race to to put out a fire on the roof. >> there is no indication at this time that this was an act of terror. there is no ongoing threat to new york city. >> hundreds of people inside the 54 story building and several other nearby buildings were evacuated. emergency crews moved pedestrians away from the street below. >> it sounded like a small